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Fuel injector pump not working

1994 GMC 5.7L. Truck was running fine, stopped for a quick store run, then truck wouldn't start. Was able to confirm that there was no fuel pressure so I got towed to a shop, they said all fuses/relays and grounds were good but found a clogged fuel filter so replaced that. Truck ran good, then 2 days later, again wouldn't start after driving til truck was warm. Shop suggested pump, made sense (truck did start after sitting for an hour)so I replaced the pump, tested connections for power and cleaned the ground up while I was in there. Again, truck ran good and started when cold, but would not start when hot, or at least consistantly. Have also replaced the relay (cheap to just check and see). 2 weeks later and now the truck won't start at all. Distributor could be replaced, have cleaned it up in the mean time. When it does start it runs very strong, no hesitation under load. Only thing I could complain about is that it will come very close to dying coming up to a stop, but a tap on the throttle gets it going again and it will idle fine. Could a faulty ignition module / coil / distributor cause the fuel pump not to prime?

Posted by Anonymous on

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Posted on Jan 02, 2017

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SOURCE: GMC 4.3 runs fine

EGR Valve

Posted on Dec 23, 2008

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SOURCE: 1994 GMC K1500. Ran great,

As per the problem which you mentioned in your question it says " Once it gets up to op temp, idles very rough, won't take fuel, eventually dies. Won't restart til cold."------- ------- Its low fuel pressure or problem with o2 sensor.----------

As per your problem mentioned, it indicates the problem with fuel pressure.-------- The fuel pressure is low.---------- First thing you can do is get the fuel pressure checked, this will confirm the problem. --------- If the pressure checked low that means problem is with faulty pump and clogged fuel filter.----------- If the fuel pressure is checked ok, then other possibility is faulty o2 sensor and crank sensor. The o2 sensors are before and after catalytic converter.-------Both the sensors are to be replaced.------ And as per you mentioned your problem, its quite possible that faulty o2 sensor will cause this problem.------ O2 sensor is the part which sends signal to ECM( the cars computer).It sends signal to computer about fuel / air mixture.How and when to send fuel to engine.--------- If o2 sends stops sending signal to cars computer then it will not send the fuel to engine.------- In your case the o2 sensor is getting overheated and this is stopping the o2 sensor from sending signal to ECM.But when your car shuts off the sensor gets cool and again it starts working.------ So as per problem, get both the o2 sensors checked and replaced.---------- Also get the crank sensor checked.--------This will help.Thanks.Helpmech.


Posted on Aug 30, 2011

  • 5280 Answers

SOURCE: 99 f250 v10 auto 4x4-cat converter imploded,

The fuel pressure sounds too low. Is it multi-port injection? Check the fuel pressure against your specs for the car and engine. MPFI systems usually require 40-50 psi.

Posted on Apr 16, 2013

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