I got asked about this
2 pumps, 1 mech,1 electric,kinda redundant type set up ?
a fuel log with a reg after the log or before the log ?
Share the same supply line?and I will use a return line also.Please help I have thought about 30 diff ways to do this ,that would work.
I just wanna do it right.
"
WELL<your trying to make the system FAR more complicated than it needs to be. READ THIS LINK
viewtopic.php?f=55&t=211
.... Id USE,one fuel pump of the correct size and type, EITHER a quality high volume electric pump mounted near the tank, or a quality high volume manual on the engine, to push fuel to a regulator with a return line to the tank, but if you mount an electric pump back near the fuel tank to feed a manual pump is not likely youll hurt anything PROVIDED your line size and fuel pressure regulator can handle the flow rates and maintain the correct pressure at the carb inlet port. a single pump is all you need in almost any street driven application, running twin fuel pumps is just extra complication, 3/8" lines are really the minimum size, 1/2" will require that you run new fuel lines, and unless the engine potentially has well over 400 hp its not likely to be necessary
heres what it will look like correctly set up with two pumps,
ideally all lines are 3/8" minimum but 1/2" id is far better
the electric fuel pump would ideally be mounted lower than the tank and as far back as practicable INSIDE the frame rails for crash protection, with a hot lead to the electric pump that only supplies electric power ,if you have oil pressure and the ignition keys in the on possition, as electric pumps PUSH fuel,far more efficiently than they PULL fuel ( to feed the manual pump if your useing a second pump, and as has been pointed out running a second manual fuel pump is both redundant and usually causes more problems tan it solves), as you don,t want the electric pump running if the engines NOT running.
the fuel filter should be mounted for easy access,as you should change it frequently.
the regulator should be mounted as close to the carb as easy access allows, with the return line back to the tank, ideally larger than the feed line for zero resistance to fuel flow
keep in mind the by-pass style regulators work by allowing all fuel flowing above a certain threshold pressure you set the regulator too,to return to the tank, usually thats set at 4.5-6 psi for carbs [/i]
keep in mind that the pressure sensor only makes tthe electrical connection once theres 5 psi of oil presure in the blocks oil passages
"Ok G.V., need your input.
I intend to wire up 1 electric pump through an oil pressure switch (GM thought of it first thats how I got the idea). If the car sits dorment for a few weeks and the fuel evaporates in the carb the engine could be hard to start. Granted, you should be able to crank 5 psi long enough to fill the carb and start the engine but this adds wear and tear to the starter. Which of the following solutions would you reccomend if any?
(1) Bypass the fuel pump circuit and power it through the start circuit so the pump powers up during engine cranking. This would need a diode so the start circuit is not back fed through the fuel pump circuit after engine start up which complicates the circuit.
(2) Wire in a toggle switch that powers the pump before cranking. Once engine starts, kill the toggle and allow the oil pressure circuit take over. The switch positions would be marked START (hot)and RUN (open). In a (heaven forbid) severe collision, the toggle could be activated (unlikely but possible) and defeat the safety built in to the oil pressure power up circuit.
What do you think?"
I would NEVER use a manual toggle switch,on an electric fuel pump they have a tendency to get thrown into the wrong possition at times, causeing all kinds of potential problems ranging from flooded carbs,engine stalling, dead batterys, burned out pumps etc.
if you want an over ride switch for the fuel pressure youll want a BUTTON (normally open contacts)that connects the circuit only while the spring loaded button is MANUALLY HELD in the depressed position, similar to the older cars starter circuit buttions, thus the circuit works with or without the button depressed if the engine has oil pressure,and you have the OPTION to pre-prime the carb by MANUALLY depressing and holding the over ride button, momentarily ,sending the electricity to the electric pump to pre -prime the carb. but the fuel,system still works either way
if your not running a return line and a return style fuel pressure regulator your nor running fuel thru the electric pump in enought voluum to keep it cool for a long life expectancy
read
http://www.centuryperformance.com/fueli ... g-140.html
2 pumps, 1 mech,1 electric,kinda redundant type set up ?
a fuel log with a reg after the log or before the log ?
Share the same supply line?and I will use a return line also.Please help I have thought about 30 diff ways to do this ,that would work.
I just wanna do it right.
"
WELL<your trying to make the system FAR more complicated than it needs to be. READ THIS LINK
viewtopic.php?f=55&t=211
.... Id USE,one fuel pump of the correct size and type, EITHER a quality high volume electric pump mounted near the tank, or a quality high volume manual on the engine, to push fuel to a regulator with a return line to the tank, but if you mount an electric pump back near the fuel tank to feed a manual pump is not likely youll hurt anything PROVIDED your line size and fuel pressure regulator can handle the flow rates and maintain the correct pressure at the carb inlet port. a single pump is all you need in almost any street driven application, running twin fuel pumps is just extra complication, 3/8" lines are really the minimum size, 1/2" will require that you run new fuel lines, and unless the engine potentially has well over 400 hp its not likely to be necessary
heres what it will look like correctly set up with two pumps,
ideally all lines are 3/8" minimum but 1/2" id is far better
the electric fuel pump would ideally be mounted lower than the tank and as far back as practicable INSIDE the frame rails for crash protection, with a hot lead to the electric pump that only supplies electric power ,if you have oil pressure and the ignition keys in the on possition, as electric pumps PUSH fuel,far more efficiently than they PULL fuel ( to feed the manual pump if your useing a second pump, and as has been pointed out running a second manual fuel pump is both redundant and usually causes more problems tan it solves), as you don,t want the electric pump running if the engines NOT running.
the fuel filter should be mounted for easy access,as you should change it frequently.
the regulator should be mounted as close to the carb as easy access allows, with the return line back to the tank, ideally larger than the feed line for zero resistance to fuel flow
keep in mind the by-pass style regulators work by allowing all fuel flowing above a certain threshold pressure you set the regulator too,to return to the tank, usually thats set at 4.5-6 psi for carbs [/i]
keep in mind that the pressure sensor only makes tthe electrical connection once theres 5 psi of oil presure in the blocks oil passages
"Ok G.V., need your input.
I intend to wire up 1 electric pump through an oil pressure switch (GM thought of it first thats how I got the idea). If the car sits dorment for a few weeks and the fuel evaporates in the carb the engine could be hard to start. Granted, you should be able to crank 5 psi long enough to fill the carb and start the engine but this adds wear and tear to the starter. Which of the following solutions would you reccomend if any?
(1) Bypass the fuel pump circuit and power it through the start circuit so the pump powers up during engine cranking. This would need a diode so the start circuit is not back fed through the fuel pump circuit after engine start up which complicates the circuit.
(2) Wire in a toggle switch that powers the pump before cranking. Once engine starts, kill the toggle and allow the oil pressure circuit take over. The switch positions would be marked START (hot)and RUN (open). In a (heaven forbid) severe collision, the toggle could be activated (unlikely but possible) and defeat the safety built in to the oil pressure power up circuit.
What do you think?"
I would NEVER use a manual toggle switch,on an electric fuel pump they have a tendency to get thrown into the wrong possition at times, causeing all kinds of potential problems ranging from flooded carbs,engine stalling, dead batterys, burned out pumps etc.
if you want an over ride switch for the fuel pressure youll want a BUTTON (normally open contacts)that connects the circuit only while the spring loaded button is MANUALLY HELD in the depressed position, similar to the older cars starter circuit buttions, thus the circuit works with or without the button depressed if the engine has oil pressure,and you have the OPTION to pre-prime the carb by MANUALLY depressing and holding the over ride button, momentarily ,sending the electricity to the electric pump to pre -prime the carb. but the fuel,system still works either way
if your not running a return line and a return style fuel pressure regulator your nor running fuel thru the electric pump in enought voluum to keep it cool for a long life expectancy
read
http://www.centuryperformance.com/fueli ... g-140.html