vapor lock, fuel percolation,cause and cure

Discussion in 'Intake Systems , Fuel Systems and Related' started by grumpyvette, Jun 19, 2010.

  1. grumpyvette

    grumpyvette Administrator Staff Member

    READ THRU THESE SUB LINKS
    http://www.estes-park-information.com/vapor-lock.html

    http://en.wikipedia.org/wiki/Vapour_lock

    viewtopic.php?f=55&t=211&hilit=inside+fuel+pump

    viewtopic.php?f=55&t=5365&p=16067&hilit=inside+fuel+pump#p16067

    http://garage.grumpysperformance.com/index.php?threads/vacuum-gauge-help.9453/#post-34623

    If you have not experiences vapor lock issues before this,its most likely because youve only dealt with high pressure fuel injection cars not carburetors, but are now recently dealing with an older carburetor equipped muscle car in hot weather, what may have (CHANGED) is either the fuel itself or the fuel pump may be dealing with wear or heat related issues, but in almost every case Ive investigated vapor lock is aggravated by the use of a fuel system thats not using a return style fuel pressure regulator.
    vapor lock is basically a fuel delivery condition caused by both heat and low fuel pressure where fuel turns to vapor in the carburetor or fuel lines , and the car won,t start as a result and the fuel pump won,t pump fuel effectively as a result.
    a return style fuel pressure regulator , like those used on most EFI systems generally help avoid vapor lock issues, for two reasons, first the higher pressure used, but more importantly, the basic design has a constant flow of fresh fuel coming up from the tank, and some routed back to the tank this tends to limit the heat level absorbed by the fuel, unlike the common carburetor dead head systems used on many early cars with carbs
    recent changes in fuel formulas to reduce emissions by adding ethanol up to 10% by volume, have changed the temperature tolerance and made the seals in the fuel system,more subject to wear, or degrading over time, issues.
    some fuel filters mounted in the engine compartment tend to aggravate the problem

    THERES A GREAT DEAL OF RELATED INFO IN THE LINKS AND SUB LINKS


    viewtopic.php?f=55&t=211

    viewtopic.php?f=55&t=635

    viewtopic.php?f=87&t=7770&p=26981&hilit=ethanol#p26981

    viewtopic.php?f=87&t=2141&p=25201&hilit=ethanol#p25201

    viewtopic.php?f=55&t=58&p=23610&hilit=+1206#p23610

    viewtopic.php?f=52&t=462&p=22497&hilit=+1206#p22497

    viewtopic.php?f=99&t=6461&p=20458&hilit=+1206#p20458

    viewtopic.php?f=52&t=5537&p=16750&hilit=+1206#p16750

    viewtopic.php?f=80&t=8505&p=32253&hilit=filter+drain#p32253

    viewtopic.php?f=55&t=5378&p=16106&hilit=+1206#p16106

    viewtopic.php?f=55&t=1038&p=14928&hilit=+1206#p14928

    viewtopic.php?f=52&t=4664&p=12584&hilit=+1206#p12584

    viewtopic.php?f=55&t=2953&p=7745&hilit=+1206#p7745

    viewtopic.php?f=55&t=2857&p=7402&hilit=+1206#p7402


    Vapor lock occurs when the gasoline in your engine turns into vapor, this is usually restricted to carburetor equipped engines, because they use a fairly low 5-7psi fuel pressure and due to the fuel lines, or fuel pump being located where the engine heat is rather high like near headers or exhaust pipes. the symptoms, commonly include,a condition where the engine runs ok until it heats up, then , your engine starts missing and has a general lack of power when the engines reved ,once it reaches operating temps,hard re-starting after brief cool down, lack of passing power and general lack of torque, due to intermittent fuel supply This can happen in cars equipped with carburetors or low pressure fuel injection due to high heat in the carburetor or fuel lines or high altitude, where gas turns to vapor at a lower temperature, more easily than normal. Often it's a combination of both heat and altitude. Essentially, your engine is no longer getting enough liquid fuel to the carburetor, or throttle body.
    A FUEL SYSTEM THAT'S PROPERLY CONFIGURED WITH A RETURN STYLE OR BYE_PASS FUEL PRESSURE REGULATOR IS FAR LESS LIKELY TO BE TROUBLED BY THIS AS THERE'S CONSTANTLY FRESH COOL FUEL REACHING THE CARB AND HOT FUEL RETURNED TO THE TANK
    READ THESE THREADs

    viewtopic.php?f=55&t=211

    viewtopic.php?f=55&t=635

    viewtopic.php?f=55&t=9305

    viewtopic.php?f=55&t=4381&p=11507&hilit=ethanol#p11507
    DON,T CONFUSE this with, running out of fuel or a defective fuel pump,or having the carburetors float level not correctly adjusted(to low or to high) causing carburetor flooding or fuel starvation that can happen when the floats are too high or too low or the fuel pump is flooding the carburetor if the fuel pressure exceeds about 5.5 -6 psi which occasionally does happen if you don,t know the difference in the symptoms
    Don,t confuse this with a similar symptom,caused by a partially plugged catalytic converter, where once the engine reaches a higher rpm level the power drops off as the exhaust becomes a major restriction to exhaust flow rates, and returns once the rpm level drops reducing the exhaust flow
    keep in mind that a return style fuel pressure regulator set at about 5 psi matched with a fuel pump that provides at least 7 psi results in a constant flow of new fresh cooler fuel reaching the regulator from the fuel tank and heated fuel bleeding off back down the return line to the fuel tank, so this type system seldom has a tendency to have vapor lock occur, but systems using the dead head style fuel pressure regulators frequently have it happen as fuel is relatively stationary in the fuel lines allowing engine heat to bake fuel lines and cause vapor to form
    READ THESE RELATED THREADS

    viewtopic.php?f=55&t=635

    viewtopic.php?f=55&t=211

    you'll want to check the, fuel tanks at least 1/4 filled,and the carburetors float levels are correct and the fuel pressure,is at between 4psi-5.5 psi and theres adequate flow at the carburetor inlet port as the first steps in diagnosing the problem

    viewtopic.php?f=55&t=211

    vapor lock,is rare to almost non-existent, in fuel injected cars due to the combination of higher fuel pressure and constant cooling flow of fuel back to the tank thru the return style fuel pressure regulator most fuel injection systems use.
    Symptoms include power loss, a feeling that the car is about to stall, a rough engine, or the car cranks but won't start.
    you can cure vapor lock by installing the correctly designed fuel supply system, if the fuel is kept under a set pressure than all fuel/vapor is prevented from forming in the line by the simple process of keeping the fuel from heating excessively by keeping it moving slowly thru the lines until its used, fuel pressure should be about 6-9 psi up to the fuel pressure regulator and at about 5 psi between the carb inlet and regulator, so you don't have that problem, use of a return style fuel pressure regulator mounted as close to the carburetor as you can reasonably mount it and if possibly running the fuel lines where they are not near a hot exhaust component, keeps a constant exchange flow of fuel in the lines with fresh lower temp fuel from the tank.
    vapor lock is basically the result of fuel brought to its boiling point pressurizing the line between the tank and carb and preventing fuel flow, keep the fuel in constant rotation thru the fuel system and back to the fuel tank with a RETURN STYLE FUEL PRESSURE REGULATOR AND RETURN LINE and the FUEL NEVER HAS TIME TO ABSORB THE HEAT TO BOIL AND CAUSE A PROBLEM.
    that's also why its a good idea to keep your fuel tank at least 1/3rd full as most modern cars use electric in the tank fuel pumps that are cooled by sloshing fuel in the tank
    Vapor lock is rare with today's fuel injection systems. Vapor lock occurs when the vapor pressure of the fuel is higher than the surrounding environment. In older engines with "sucking" fuel pumps at the engine, the pressure in the fuel line to the tank was reduced by the sucking action of the fuel pump drawing fuel form a fuel tank nearly twenty feet away, and when heated, the gasoline actually boiled creating a vapor of gasoline which the fuel pump could not handle, thus the name "vapor lock"., as pressure is reduced in the fuel line the boiling point of the fuel is reduced.
    gasoline in some blends will boil as low as about 120F if the fuel line pressure is low enough and a fuel pump can,t SUCK vapor efficiently, pumps PUSH FUEL FAR MORE EFFICIENTLY than THEY PULL FUEL SO AN ELECTRIC PUMP MOUNTED LOWER THAN AND NEAR THE TANK IS ABOUT IDEAL

    Today's fuel pumps are in the fuel tank where they push the fuel under pressure to the engine systems. Excessive fuel which is not used is sent back to the fuel tank. This causes a constant flow of pressurized, cool fuel in the lines to the engine system, be it fuel injection or carburetor. As a result you would have to heat the fuel line with a propane torch to get the fuel to boil and even then it would be cooled by the flowing fuel circulating from the tank to the engine and back again to the tank. Vapor lock as we once knew it is a thing of the past.

    http://www.chevyhiperformance.com/tech/ ... index.html

    [​IMG]

    viewtopic.php?f=55&t=635

    http://web.archive.org/web/200701062316 ... 1.htm#FPHP

    http://www.vw-resource.com/vapor_lock.html

    viewtopic.php?f=32&t=596&p=793&hilit=+filter+fuel+drain#p793

    QUOTE

    Vapor Lock

    ~~~

    Have you ever had this problem? You are driving home from work late in the afternoon. It's 90oF (32oC) outside and there's lots of traffic, so accelerating and decelerating a lot. The engine is working, and you know it's getting hot.

    Then, about 4-5 miles from home, the engine suddenly starts surging and then decides to take a rest altogether. As you pull off the road you think to yourself, "This couldn't be an electrical problem - the engine wasn't actually cutting out, just surging."

    Alternately, you drive to the store on a hot day (far enough so that the engine gets thoroughly hot); when you return from the store to the car, it won't start! What's up with that!?

    So you lift the engine lid and notice right off that there is no fuel in that small fuel filter in the line between the fuel pump and the carburetor (if you have such a filter -- we actually recommend that you don't have a filter here). So right away you know the problem (right?) - vapor lock! Every VW we have had has done this when it got hot. They seem to be especially touchy both when they're hot and when it's getting close to "Tender Loving Care" time, when timing or valves may be a bit off the numbers.

    The usual problem is that the whole engine gets thoroughly hot, and when you switch off, there is a 'heat soak' period when the temperature in the tinware and engine compartment rises because the residual heat in the cylinder/heats isn't getting blown away by the fan. The heads run at about 265-285oF (130-140oC) and can run up to about 355oF (180oC) on a really hard run which is pretty hot.

    This causes the metal fuel line around the tinware, the fuel pump, and the carburetor to all heat up somewhat, causing either excess vaporization of the fuel in the carburetor, or and actual vapor lock in the fuel line or fuel pump.

    As a result, starting is sometimes hard. With hot fuel in the carburetor, the least reduction in pressure (through the carburetor throat) causes instant vaporization, perhaps of fuel in the float bowl too (which breathes into the top of the carburetor throat), and of course a vapor lock in the fuel line or pump is even worse, because it will result in an empty fuel bowl in the carburetor - the car uses that fuel and stalls because it can't get any more. Then it takes a lot of cranking to fill the fuel bowl, once the vapor lock itself is cleared.

    In summary, following is the cause and the cure for vapor lock -

    Cause: The engine overheats, causing the fuel line, fuel pump and carburetor to heat up.

    Result: Excess vaporization of fuel in the carburetor and/or actual vapor lock in the fuel line or fuel pump.

    Cure:

    1. Wrap the fuel lines on both sides of the pump with aluminum foil.

    Note: This is a precaution if your car is prone to vapor lock. It won't help much once the problem has
    already occurred.

    # Pour a little water over the fuel pump to cool and re-condense the fuel, being careful not to splash the distributor. If no water is readily available, hopefully there is some in the windshield washer bottle. It doesn't take much.

    # Hold the throttle open just a bit with the accelerator pedal while you crank. Don't move the throttle at all while cranking, or the accelerator pump with flood the carburetor. The reason for cracking the throttle open it to avoid using the idle jet alone, as this runs the car richer than the main jet, and a rich-hot mixture makes the car flood easily.

    # When the engine catches, hold the throttle still until it clears the excess fuel (revs up smoothly).

    Away you go!

    ~~~

    Other things to check if vapor lock has become a regular problem:

    * Is the heat riser under the inlet manifold getting too hot? It should be hot enough to keep the manifold above it warm, but if the heat riser is providing excessive manifold heat, it can also be overheating the fuel line which runs close to it on the way to the fuel pump. There are "small hole" heat riser gaskets available (you'll have to look for them though) which can reduce the heat flow through the heat riser if it's running finger sizzling hot.

    * Is the carburetor running lean? Many new H30/31 and 34PICT/3 carburetors are supplied with lean jetting as an emissions thing, which makes the engine harder to tune, and causes higher engine temperatures. There is information elsewhere in these articles about suggested jetting for various distributor, engine size and carburetor size options.

    * Is the carburetor pre-warmer working properly? The paper tube up to the carburetor inlet is supposed to draw air from near one cylinder head to speed up the engine warm-up process, but if it's stuck full on (breathing hot air) the engine will run hotter than it needs to, which will worsen any potential vaporization problem. There are two actuating mechanisms - the earlier engines (up to about '71-'72) have a pull-wire operated by the right hand cooling flap assembly, and later engines have a vacuum line from the manifold directly under the carburetor, up to a temperature switch in the air cleaner and another vacuum line from that switch to the vacuum canister on the side of the air cleaner inlet. The early type is just on-off, depending on whether the flaps mechanism (controlled by the thermostat) is open or shut, but the later type may hold a partial position, depending on the temperature inside the air cleaner. Of course if your engine has no cooling flaps (tsk tsk) or if it has no vacuum lines connected, or an aftermarket air cleaner, then the carburetor inlet will be breathing full cold all the time - a potential icing problem, but not an excess-heat problem.

    * Is any of the tinware missing?. If the engine is missing any of the tinware which controls the flow of cooling air around the heads and cylinders, it WILL run hot, and this will worsen any vapor lock problems.

    * Is the engine tuned properly?. If the car is out of tune it has to work harder to provide the power to drive the car, so it may run hotter. Keeping the car well tuned keeps the engine temperatures in the normal range, minimizing any vapor lock problems.

    ~~~

    Notes from Rob on the Subject of Vapor Lock -

    My '68 Bug definitely doesn't like the heat as much as my '70 Bug - he started getting vapour locks before we even got there, and was troublesome all the way home. Luckily I had a bottle of water with me and was able to pour a little over the fuel pump and carby, and get him going each time.

    I think the problem is that the heat riser is working TOO well, and cooking the inlet manifold and carb plus the fuel pump.

    I'm going to make a block-off washer for one side of the heat riser, and see what effect that has. It's only about 20 minutes to install it and will be a good test of the theory. I can always drill a tiny hole in it if I find the carby freezing up. He already has a "small hole" washer in one side, but the inlet manifold still gets finger burning hot, and it only needs to be slightly warm to keep the fuel in suspension.

    I cut a washer out of flat metal sheet, and it only took about 20 minutes to remove the rear tinware, pull the two heat riser bolts and slide the old washer out before putting the new washer in. I found that you can use the tinware to "lever" on if you are careful - I used a piece of flat steel so I was spreading the load, and it only took a little levering.

    I've only had a couple of short runs so far, but the manifold under the carburetor is not completely cold, so it looks like it might work OK. If not, I'll remove the seal and put a 1/16" hole in it and work up from there.

    The manifold has always been too hot to touch on my '68 Bug and it only needs to be warm ( above freezing) to keep the fuel in suspension. He seems to have a littel more power now too - and a hot inlet WOULD be less dense, so that makes sense.


    http://www.wisegeek.com/what-is-vapor-lock.htm

    Vapor locking primarily happens in cars with carbureted engines, but since electronic fuel injection replaced carburetors in the 1980s, most car owners don’t have to deal with vapor lock anymore. Carburetors and electronic fuel injection are two different methods of delivering the proper amounts of fuel to the engine. Fuel injection is more advanced, and requires a computer to tell the injectors how much gasoline to squirt into the engine. A carburetor, on the other hand, is a mechanical device that uses the engine’s natural vacuum, allowing specific amounts of fuel to be sucked into the combustion chambers. The amount of fuel that is delivered to the engine can be changed using simple mechanical adjustments on the carburetor.

    Most carbureted engines have a mechanical in-line fuel pump, which means that the simple mechanical pump is placed on the fuel line, usually next to the engine. The mechanical fuel pump’s proximity to the engine means that the engine’s heat causes the fuel in the line to become very hot. When the fuel becomes too hot, it turns into a vapor, just as water begins to turn to steam when it boils. This process is hastened by the vacuum created in the line as the fuel is sucked into the engine.

    When the fuel turns into vapor, the mechanical fuel pump can no longer move it along the lines. As a result, some or all of the fuel stops getting into the combustion chambers, and the car either begins to run very roughly or dies completely. If the driver attempts to restart the car, it will probably not start, or will continue having problems. This is known as vapor lock.

    Vapor lock does not usually happen in fuel-injected engines for several reasons. First of all, most electric fuel pumps are located at or in the fuel tank. Because the fuel tank is usually located too far away from the engine to be affected by its heat, gasoline is not likely to turn to vapor there. As a result, the fuel pump can push the fuel along without any problems, avoiding one of the major causes of vapor lock.

    Another reason why vapor lock does not often happen in fuel-injected engines is because the fuel lines are usually pressurized. The high pressure that the fuel is under prevents it from turning into vapor quite as easily, unlike the carbureted system that actually produces negative pressure, also known as vacuum, in the lines.

    More efficient engine cooling systems also contribute to the decreased likelihood of vapor lock occurring in modern cars. The cooling fans in older cars usually ran off of the momentum of the engine, which meant that when cars were at a disadvantage when they sat idling in traffic for long periods of time: The lack of motion meant less air flowing through the engine compartment, and the fan — stuck at the idling speed of the engine — was unable to cool the engine sufficiently. As a result, the engines in older cars tend to run hotter in heavy traffic, making vapor lock more likely to occur.

    Modern cars, on the other hand, typically have electric cooling fans. These fans are linked to a sensor that detects the engine’s temperature, and tells the fan whether to speed up or slow down. As a result, the internal combustion engines in modern cars are less likely to overheat than those in older models, making vapor lock much less common than it used to be.

    All of the problems that cause vapor lock are easily corrected, even on older cars. Older cars can often be retrofitted with the newer technology that reduces the likelihood of the fuel lines overheating. For instance, even on a carbureted engine, a low-pressure electric fuel pump can be installed near the fuel tank, which will keep the fuel moving along the lines even if it starts to heat up in the engine compartment.

    Another easy remedy for vapor lock in older cars is to install an electric fan in the engine compartment. Many auto parts stores carry aftermarket cooling fans, which can be installed on any car. Some cooling fans can be connected to the existing engine temperature sensor, mimicking the behavior of the cooling fans in modern cars.

    Finally, vapor lock can be prevented in any car by protecting the fuel lines from the heat of the engine. There are two ways to do this. One way is to install heat shields between the engine and the fuel lines, which will divert most of the heat away from the lines. Fuel lines can also be insulated to prevent the fuel from getting to the temperatures at which vapor lock occurs.

    READ THESE related threads

    viewtopic.php?f=55&t=211

    viewtopic.php?f=55&t=635

    viewtopic.php?f=55&t=1030

    viewtopic.php?f=55&t=109

    viewtopic.php?f=55&t=231

    viewtopic.php?f=55&t=6442&p=20373&hilit=brass+roof#p20373

    viewtopic.php?f=55&t=4381

    viewtopic.php?f=56&t=495&p=8333&hilit=+back+pressure#p8333

    http://www.centuryperformance.com/fueli ... g-140.html
     
    Last edited by a moderator: Mar 22, 2016
  2. grumpyvette

    grumpyvette Administrator Staff Member

    testing your fuel pump

    IF you suspect your fuel pump is not supplying the correct pressure or volume of fuel to the carb,
    its fairly simple to verify or test.
    verify your carb float levels, and check for vacuum leaks,and replace the fuel filter, first,
    but to test the fuel pump,
    you'll need a fuel pressure gauge

    http://www.harborfreight.com/fuel-injec ... 92699.html
    [​IMG]

    HF sell for under $20
    [​IMG]
    to determine if your getting at least 5 psi,use the test gauge, between carb and fuel pump, and if you are, then and if you are ,disconnect the fuel line from the carb , add a section of fuel line so you can easily let the pump push fuel into a large container like an empty milk or bleach gallon container you set on the floor and have a friend stand by with a fire extinguisher or at least a garden hose so that if you do manage to start a fire your ready to contain the resulting problem,have the friend hold the fuel line in the container while you start the car and time the test,if its a manual pump, allow the engine to idle on the fuel in the carb, and run for 30 seconds (YES TIME IT!)if its electric just turn on the pump for a timed 30 seconds,then measure the unrestricted fuel flow volume,with a large measuring cup, or quart container, like an empty oil container by pouring the resulting fuel flow you caught in the gallon container during the test,it should be no less than 1 quart minimum.

    if your getting BOTH a minimum of 1 quart every 30 seconds AND 5 psi your marginal, but usually going to be ok for a basic street car, fuel supply.
    if you get less than 5 psi or less than 1 quart of fuel in 30 seconds of unrestricted flow the pumps at least highly suspect or more likely faulty, and should be replaced, you should be getting at least 2 quarts, 1 quart in 30 seconds is PATHETIC AT BEST
    in most cases you'll have closer to 2-3 quarts of fuel in the gallon container , if you have a decent quality fuel pump and have a pressure reading 6-8 psi and you'll need your friend to hold the fuel line into the gallon container or its likely to jump out and throw fuel around if un-restrained as the fuel jets out, so be aware of the potential spilled fuel/fire hazard


    heres a few fuel pumps, notice the unrestricted flow is over a gallon a minute


    http://www.summitracing.com/parts/EDL-1722/

    http://www.summitracing.com/parts/EDL-1721/

    http://www.summitracing.com/parts/CRT-M4530/

    http://www.summitracing.com/parts/CRT-M6101/

    http://www.summitracing.com/parts/SUM-G3136/

    http://www.summitracing.com/parts/CRT-P4070/

    http://www.summitracing.com/parts/MRG-95H/

    naturally having a fuel pressure gauge mounted to the carb inlet feed makes diagnosing problems faster

    [​IMG]
    http://www.summitracing.com/parts/MRG-2975/
    [​IMG]
    http://www.summitracing.com/parts/HLY-26-504/


    read these threads and sub links
    viewtopic.php?f=55&t=3172&p=8456#p8456

    viewtopic.php?f=50&t=1660&p=4484&hilit=+bending+tube#p4484

    viewtopic.php?f=55&t=635

    viewtopic.php?f=55&t=1030

    viewtopic.php?f=55&t=1939

    viewtopic.php?f=55&t=1442

    viewtopic.php?f=55&t=1860

    viewtopic.php?f=55&t=733&p=3587&hilit=cell#p3587
     
  3. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    i just read the part about vapor lock and i think thats the exact problem i have! i didnt know the intake was not supposed to be extremly hot to the touch. Because mine is and also my carb gets very hot to the touch. and i notice when i give it gas, i see the gas squrting out then turning to vapor right away. But how dod i fix it?
    My electronic fuel pump is near my gas tank so i dont think thats getting hot.
    But i know the gas line that goes from the pump to the regulator is under the exhaust. Buts its always been there i never had a problem before.
    i took apart my carb and clean it and adjusted the floats and it happened again tonight when i test drove on the highway, but then when i got close to my home i lost power and was just stumbling home.
     
  4. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    obviously I,m not on site and can only go by what you tell me to diagnose the problem
    if theres anything youve changed recently and the car was running ok before that change then obviously that is the first place you look for a cause.
    step one, drop back to basics and check everything
    verify your current fuel pressure at the throttle body inlets.
    vapor lock is not a frequent problem with fuel injection because even with your cross-fire throttle body injection you normally run in the 11psi-17psi range which tends to reduce the tendency for fuel to boil in the fuel lines
    you also have the option to fill the EGR port thru the intake manifold with aluminum welding which will reduce the manifold temps but it will also cause the CPU to throw trouble codes
    verify ignition timing and firing order and TDC

    the original crossfire intake is PATHETIC in its potential flow at best,as are the heads and cam and the combo is very RESTRICTIVE to making power, But you do have options.

    for many years, your most effective option was swapping to a custom modified OFFY or SY1 intake, that was the best option, these carb intakes were designed for maximum power in the 3500rpm-7000rpm range so they were, not ideal on a mildly tweaked nearly stock engine that retained most of the stock components, but they did give you the potential to build an engine that significantly out powered the stock crossfire, but it was a trade-off that really required several other mods to get those custom intakes up to their full flow/power and rpm potential, but remember that both the heads and cam needed to also be upgraded and the rear gearing or converter stall would need to be also upgraded in many cases to take full advantage of the increased flow rates,but theres a renegade intake available now, that gives you an off the shelf option, designed to work with the factory components OR give you a bit more flow allowing you to gain more power with those optional upgrades or still work better than the stock intake without the upgrades (obviously use of better heads and a larger cam, with the intake swap, have more potential)



    HERES SOMETHING FAR SUPERIOR, to stock fuel filters if you need something better
    [​IMG]
    http://www.aemelectronics.com/universal ... ilter-1212


    KEY FEATURES
    Machined from 6061-T6 aluminum and hard anodized black
    Flows up to 12.32 gpm @ 45 PSI and 2.63 gpm @ 6 PSI with -10 port fittings
    Filters as low as 7 microns
    Viton o-rings and gaskets ensure outstanding performance when using gasoline, alcohol or gasoline/alcohol blended fuels
    End caps are machined with -10 AN female fittings with o-ring receiver groove
    End caps have pressure intensifiers for greater sealing of end gaskets
    2” OD x 10” length for easy mounting
    Commonly available replacement filter cartridges
    Laser etched with AEM logo, flow and filter replacement information

    The AEM High Flow -10 AN Inline Fuel Filter is CNC machined from 6061-T6 Aluminum and Hard Anodized Black. AEM’s engineers designed this filter with the racer in mind and with the intention of maximizing flow, filtration and ease of installation. The end caps are machined with -10AN female fittings with o-ring receiver groove that allow the filter to flow up to an astonishing 12.32 gpm @ 45 PSI and 2.63 gpm @ 6 PSI. All sealing o-rings and gaskets are made of Viton for outstanding performance when using gasoline, alcohol or gasoline/alcohol blended fuels. The commonly available replacement filter cartridges filter as low as 7 microns. The standard 2” OD allows for easy mounting virtually anywhere in the vehicle.
    read thru the links and sub links

    viewtopic.php?f=32&t=1148&p=5322&hilit=+crossfire#p5322

    viewtopic.php?f=2&t=3064&p=8136&hilit=renegade#p8136

    viewtopic.php?f=48&t=2828&p=7301&hilit=firing+order#p7301

    viewtopic.php?f=44&t=773

    viewtopic.php?f=32&t=1401
     
  5. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    well its not a crossfire anymore. its a carb. and my carburetor gets very hot when i drive it.
     
  6. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    if you've got the hood clearance , you can use the well proven trick of installing a heat barrier between the intake and carb bases,
    phenolic spacers work well just don,t get the cheap plastic knock off versions that warp and leak, and be aware that the dual plane intakes tend to work best with the 1"and 2" four hole designs but single planes tend to work best with the larger single open plenum designs
    if you have the room under the hood a heat barrier and phenolic spacer do a decent job of reducing heat from the engine effecting the fuel in the carb, but I'll point out that the return style fuel pressure regulators keep fresh and cooler fuel at the carb inlet port , thats generally a great help unlike the dead head style of fuel pressure regulators
    [​IMG]
    http://www.summitracing.com/parts/hly-108-70/overview/

    [​IMG]
    http://www.summitracing.com/parts/SUM-G1404/

    HEAT BARRIER TYPE SPACER
    if your having heat issues like carbs with fuel boiling from engine heat in the intake,a aluminum and gasket heat barrier plus, like the one below with a 1" phenolic spacer placed above it will usually reduce heat transfer rates significantly, as the heats transferred to the engine compartment air before it can get thru the layered barriers
    [​IMG]

    http://www.jegs.com/i/Mr-Gasket/720/371 ... tId=743789
    a wood fiber carb spacer can do a great deal of heat insulation between the carb and intake manifold, its better than aluminum or phenolic as a heat barrier, and surprisingly they work great and seldom cause problems when correctly installed
    Ive measured a reduction of carb temps of over 50 degrees on some cars with an IR heat gun on the fuel bowls
    (one more good reason to have a decent IR temp gun in your tool kit)
    viewtopic.php?f=44&t=579&p=743&hilit=+infrared+tuning#p743
    http://www.summitracing.com/parts/EDL-8720/?rtype=10

    [​IMG]

    http://www.summitracing.com/parts/EDL-8725/?rtype=10
    [​IMG]

    you can also use intake gaskets with small metal plates blocking the exhaust cross over passages that usually further reduces the intake manifold temps.(notice the two small blocking plates at the top of the picture)

    http://garage.grumpysperformance.com/index.php?threads/setting-up-your-fuel-system.211/

    http://garage.grumpysperformance.com/index.php?threads/fuel-pressure-regulators.635/

    [​IMG]

    or at the ends in this picture below
    most large hardware or home improvement stores sell (tin/caps...brass plated tin sheet steel disks
    [​IMG]
    about 1.65" in diam that look like plated thin tin sheet steel that you can use ) yes they can occasionally burn through over thousands of miles of use but they cost next to nothing but a few cents to replace if that happens, the discs are use in roof repairs that can easily be modified with tin snips to function correctly for a few cents
    most bbc intake gasket sets come with exhaust block plate inserts

    [​IMG]

    Id get a IR temp gun and verify the engines operating temps but remember to verify the coolant and oil capacity are correct.

    infrared thermometers are a very useful tool to track down issues with tuning, or mal functioning sensors , without verified facts your guessing.
    this is the most consistently accurate I.R temp gun I've used for testing


    http://www.testequipmentdepot.com/e...1100200223789&utm_content=All Extech Products
    INFRARED TEMP GUN
    BTW, if you want too theres a few extra hp, available if you use an air-gap style intake manifold ,
    without any problems, you can just block both sides of the exhaust cross over passage,
    in the intake manifolds that have one even with a lifter gallery oil shield in place,
    the engine heat will be more than adequate too vaporize fuel droplets in the plenum,
    once the oil and coolant temp reaches operational temps
    naturally outside air and engine compartment air temperatures will effect the manifold plenum temp and blocking off the manifold exhaust gas cross over will tend to slow the rate of heat build-up and peak heat reached ,some what but if you check with the infrared temp gun you might be amazed to find the temperature difference of the plenum after either intake design reaches operational temps is rarely lower than about 170f f-180f on the air-gap style even with rather cool outside air temps and thats certainly sufficient heat to vaporize plenum fuel droplets.
    [​IMG]
    [​IMG]
     
    Last edited by a moderator: Jun 28, 2018
  7. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    ok thanks. i just know mine is more then 50 degrees. its burns my fingers when i move the trottle. but why isnt that i had thisproblem before? could cheap gas cause this too?
     
  8. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    hey i forgot i had this when i had to buy another fuel guage. this is what your talking about to use to measure fuel presure right?
     
    Last edited by a moderator: Aug 30, 2017
  9. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    that ADAPTER (or the one that comes with the HF gauge, or this one from summit racing)
    [​IMG]

    http://www.summitracing.com/parts/MRG-2975/

    and a fuel pressure gauge, giving you an access point to read the fuel pressure, is all you'll need, to measure fuel pressure, temporarily splice it into the carb feed line BETWEEN the FUEL PRESSURE REGULATOR AND THE CARBURETOR INLET




    [​IMG]

    http://www.harborfreight.com/fuel-injec ... 92699.html

    [​IMG]

    http://www.summitracing.com/parts/HLY-26-504/


    http://www.knizefamily.net/minimopar/fuelsystem.html
     
  10. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    well i put the fuel guage between the regulator and carb and it read at a steady 5psi which u said is good. so now i really think its my carb. i also spray more carb cleaner to check for vacumm leaks and i think i found some on the the bottom gasket of the carb on the trottle side. so i going to replace the gasket and see if that works
     
  11. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    well i fix the vacumm problem because i only had three bolts hold the carb down instead of for so i got another and tighten it down. But my problem is still there. low idle then shuts off.
     
  12. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    recheck for more vacuum leaks after replacing the gaskets and after taking the carb off the engine and placing its base on a sheet of glass to check if the base is warped, then if the base is flat replace the gaskets, and adding the insulating carb spacer would be a good idea,turn the idle adjustment screws in til they bottom out in the carb then back them out 1.5 turns,turn the linkage adjustment throttle stop open to the point the engine idles at about 850rpm

    read this link

    viewtopic.php?f=55&t=1820&p=4717&hilit=+edelbrock+carb#p4717

    viewtopic.php?f=44&t=621&p=831&hilit=+edelbrock+carb#p831
     
  13. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    well i check for warp and vacuum and it seems fine. I also double check the timing and its fine. but it still wont keep a start. now it stays on in park but when put in gear it idles for a little then shuts off. Fuel psi is at 5. and i read that from guage i put between the regulator and carb inlet.
     
  14. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    here is a video of how it idles. i set it high so it wont die. it starts at 17 then when i put in to gear is stays at around 10 for a bit then drops to 5. i about to give on this car or just buy a new carb. :lol:

    http://www.youtube.com/watch?v=8ZoRkrxsUTE
     
  15. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    when ever you have issue,s you drop back to the basics
    I REALLY WISH I COULD BE ON SITE, TO HELP!

    Id verify that the TDC on your damper and timing tab truly indicate the real TDC (TOP DEAD CENTER)
    because if they are off a bit timing the cars hopeless and on a 25 year old car thats not 100% certain

    viewtopic.php?f=52&t=966&p=6800&hilit=stop+dead+center%E2%80%A6#p6800

    viewtopic.php?f=70&t=1015&p=1864&hilit=tabs+tape#p1864

    viewtopic.php?f=70&t=875&p=6241&hilit=tabs+tape#p6241

    ID adjust the valves while it idles to 1/4 turn in from the point that the lifters just stop clicking

    viewtopic.php?f=52&t=196

    ID carefully inspect the firing order on distributor cap & the plugs and post clear pictures of the plugs as it gives a great deal of info

    Id verify the coil polarity

    viewtopic.php?f=70&t=3301&p=8745#p8745

    Id also recheck for vacuum leaks and refer to the edelbrock carb link on tuning I posted

    viewtopic.php?f=62&t=882&p=1390&hilit=vacume+leaks%E2%80%A6#p1390

    viewtopic.php?f=48&t=2828&p=7301&hilit=firing+order#p7301

    BTW just a question, or two
    how long has it been since the cams timing chains been changed or a cams been installed?
    are you sure the catalytic converter is functioning correctly or is there a chance its are clogged
     
  16. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    the cam and timig chain are brand new. they were installed a couple months ago but the car not driven because the body was apart and i been sanding it and puting it together. Everything on the car is new. spark plug wires, dist and dist cap,

    i was thinking maybe i used really cheap gas too?
     
  17. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    let me clear this up in my mind,any time you make a change and experience a problem after the change you'll want to at least consider the possibility no mater how remote, you think it is, that the change you made had some effect, and/or caused the problem or at least allowed it to occur.
    as I understand it, your stating the problem started only after you installed a new cam and timing chain?
    and Id bet you installed it dot-to-dot , and not degreed it in?
    IM not saying thats the cause but ID sure take the time to look into that carefully as it is suspect!

    if thats true these a very good chance the cams indexed incorrectly, you would not even be in the first group of 10,000, guys who ever got the cam installed a few degrees out from its intended location if thats true, so don,t think it can,t happen to ANYONE, we all learn the hard way to triple check, ID bet 50% or better of the cams, installed by hot rodders, using the timing set index marks alone to align them are at least a couple degrees out from where they are expected to be.

    you really need to recheck, especially if you didn,t use a cloyes timing set and a brand name cam, as some of the import stuff really has less than quality inspection, but its very easy to make mistakes, so at this point Id pull the timing cover and recheck very carefully...............yes IM fully aware your 100% sure its correct! you sure won,t be the first guy that was "100% sure its correct!" only to find on careful cross checking thats its NOT!
    [​IMG]
    [​IMG]
    you would not be the first guy to use the wrong index marks to align a cam, or to get it a degree or two out of alignment
    viewtopic.php?f=52&t=90
     
  18. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    yeah i know what you mean because thats what i did the first time i installed the cam. i had the timing gears set wrong but i already fix that problem and its set to the correct tdc. i have not been messing with my car lately but the other i started it and it idles fine. its just when its in gear its doesnt sound right and then when i drive around the block for a few minutes thats when it losses power then dies out on me. i just find a local guy who knows about carbs to look at it.
     
  19. grumpyvette

    grumpyvette Administrator Staff Member

    Re: vapor lock, cause and cure

    if you were local Im sure I could isolate and cure the problem reasonably fast , but unfortunately I can,t get all you guys to move down within about 15-45 minute travel time, of my location for some odd reason
     
  20. fast84vette

    fast84vette Well-Known Member

    Re: vapor lock, cause and cure

    well on a update on my car. its runs so much better now and i dont know why. the only thing i did was put gas ha. MY car car ran out of gas while working on it at home so i decided to get a gallon of better gas at a valero gas station instead of those small corner ones. and since then it hasnt have that problem no more. :)
     

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