pick-up v8 tb just stopped running

[grumpyvette]

"GRUMPY< my throttle body 350 v8 injected pick-up, just stopped running , it starts if I spray lighter fluid in the throttle body and I hear the pump run, but Im stumped, what do I check?


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start with pulling trouble codes and reading these links and SUB LINKS, get a multi meter and a shop manual, and verify your getting fuel pressure at the throttle body or fuel rail that matches what the shop manual indicates.

a simple step bye step approach where you verify function of each separate component will quickly isolate and allow you to fix the defective link in the process. don,t guess, check, and verify.
check all your fuses if you don,t have any trouble codes , if you do have trouble codes use the SHOP MANUAL to locate the problem
just because you hear the pump run does not indicate its providing fuel flow or pressure, and even if it pumps fuel it won,t provide pressure until the fuel pressure regulator restricts flow back to the tank.
throttle body injection requires a fuel pressure regulator to provide a certain minimal fuel pressure level to get the injectors to flow fuel, if the fuel pressure regulators defective the fuel flows past the throttle body injector basically unrestricted back to the tank and theres no pressure available to spray fuel into the engine, so ID strongly suggest looking up the factory suggested fuel pressure and checking your getting that at the injector/throttle body, with a reliable fuel pressure gauge, many older throttle body injection systems operate at about 14psi-18 psi , some of the more recent versions operate at 55psi-60 psi, but check your shop manual or verify the expected pressure level
http://www.harborfreight.com/fuel-injec ... 92699.html

READ THESE LINKS IN THIS THREAD POST, IF YOU HAVE QUESTIONS ASK! [/color]
http://www.howstuffinmycarworks.com/GM_ ... ssure.html

http://www.ehow.com/how_6637877_change- ... lator.html

http://www.ehow.com/list_7907357_fuel-s ... erado.html

http://www.underhoodservice.com/issue/a ... ntid=39820

if you find fuel reaches the throttle body thats good but it also must have pressure to work at the injector/throttle body , and a defective fuel pressure regulator will cause the symptom your describing, temporarily blocking the return line will be a quick test, because restricting flow will allow required pressure to build , if it runs its a good indication the pressure regulators defective
your fuel supply is laid out in similar fashion to this , but with a single or duel throttle body injector vs the multi port bank of injectors like in a TPI

 

[87vette81big]

I have & drive a 1994 GMC Suburban K1500 4X4 TBI 350.
Familiar with their unique quirks or problems as they get older.
As Grumpy said, check fuel pressure with a TBI adapter Fuel pressure gauge set & make sure it is in specs.
The injectors have a problem of shorting out due to E10 ethanol gas eventual. A resistance or impedance test will confirm. About 1.4 to 2.0 Ohms is OK. Check each injector, must match within .1 to .2 or 1 tenth to 2 tenths resistance of each other.
The injector electrical clips can come loose & or the terminals spread open & make a poor or no continuity connection sometimes.
The TBI distributor has a problem with the upper bushing going bad with lots of miles. The spinning rotating magnets will rub against the fixed poles & pickup coil. Also check the resistance of the pickup coil, should measure about 850 to 900 ohms.
Sometimes the ignition module will still fire a spark but dwell becomes fixed, variable dwell not working as it should, can be verified with an old school dwell meter or Snap On or SUN ignition oscilloscope. Dwell should be 4 to 8 degrees at idle speed. And climb or expand to 28 to 32 degrees by 3,000 RPM's.
Dwell testing procedure not listed in GM service manuals or Chilton's. My own devised test I use & have since my days in the GM Dealerships as a Master mechanic.
Check the fuel pump relay on the firewall underneath that black plastic cover. Be a large oval shaped relay black plastic housing. I confirmed failures with them in past troubleshooting no starts on TBI 305, 350, & 4.3L V6 TBI trucks & SUV's.

Brian R.