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Will start - Wont start

12bowtie

By 12bowtie
in Ask A GM Technician

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12bowtie New Member

12bowtie

Posted
Posted

My wife has a 1994 Chevy Suburban with 350 engine, bone stock. Power to fuel pump is intermittent. Most of the time it will start fine, but sometimes no start. Fuel pump has been replaced, all fuses are good, fuel relay replaced, and oil pressure switch replaced. I am an old gear head still driving a 71 chevelle. No problem fixing the chevelle, but these electronics in the Suburban are giving me fits. Any help would be appreciated. Thanks Tom

12bowtie New Member

12bowtie

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Thanks S C

Could be a loose or bare wire, but have not seen any. My gut feeling is that whatever sends current to the fuel pump for those few seconds of "primming" is the problem. Every time the suburban starts I hear the fuel pump run for several seconds. If I dont hear the fuel pump it will not start. Is there some sort of primmer switch/circuit for the fuel pump???.

SPARK CHASER Enthusiast

SPARK CHASER

Posted
Posted

According to the drawings I have, when you turn the ignition switch to the "on" position, the ECM sends a signal to the fuel pump relay to close. When that relay closes,the fuel pump should run even with the engine off. The pump has it's own regulator switch with turns the pump on or off depending on fuel line pressure. The oil pressure fuel pump switch sends a signal back to the ECM that tells the ECM it's ok to fire the fuel injectors. I would assume that if you lost all oil pressure the engine would shut itself off.

 

Either you got a bad wire,connector or your ECM has a problem,if you have already replaced the fuel pump,relay,and switch as you have said. I'll bet it's a wire or connector. If it was an ECM problem, I don't think you would ever have it start at all.

gdoug Enthusiast

gdoug

Posted
Posted

When you don't hear the fuel pump come on are the lights on on the dash with the key on? I had an intermittent problem like you described and it turned out to be the ignition switch. Mine was on a 96 but yours is a 94 which is different. My 96 would crank the engine, but no power was getting to the ECM or the fuel pump.

 

Hope this helps.

  • 4 months later...
doliver New Member

doliver

Posted
Posted

What did you find on this problem? You are describing my problem exactly. Sam problem with two different ECMs, fuel pumps, and fuel pump relays.

  • 5 weeks later...
  • 2 weeks later...
tkeeton New Member

tkeeton

Posted
Posted

I have a 1992 GMC vandura. I am having a fuel problem as well. I lost the fuel pump and replaced it and the fuel filter. after I got it started it will run for about five minutes then die. I re-prime it then it runs for a few minutes then dies again. Now I can't get it started at all again. Any suggestions?

atboley Enthusiast

atboley

Posted
Posted
My wife has a 1994 Chevy Suburban with 350 engine, bone stock. Power to fuel pump is intermittent. Most of the time it will start fine, but sometimes no start. Fuel pump has been replaced, all fuses are good, fuel relay replaced, and oil pressure switch replaced. I am an old gear head still driving a 71 chevelle. No problem fixing the chevelle, but these electronics in the Suburban are giving me fits. Any help would be appreciated. Thanks Tom

 

As long as your sure that you have no fuel pressure when the happens and the pump is not comming on,

since it sounds like you have replaced everything else, your ignition switch is a very likely cause...

just be sure to check terminal tensions everywhere, make sure the terminals arent opend up to much and

there is no damaged wires, wiggle the wires at the pump and at the oil pressure switch, the ecm and at

the relay while its running and see if it stalls, just because a wire looks fine, it could still be broken under the insulation...

maybe try tapping the ignition switch switch which is located neer the base of the column(it is not by the steering wheel) and see if it dies. or wait till it acts up and tap the switch and wigle the wires and see if it starts... just make

sure that you for sure do not have fuel pressure, you dont wanna be chasing a problem you dont actually have...

  • 3 weeks later...
essentialcycle Enthusiast

essentialcycle

Posted
Posted

Cool website! I agree myself with checking your wiring and all relays. The ignition module could also be the culprit. On some of the full size trucks, there is a fuel pupm jumper. It usually has a green single connector that you can use a fused jumper to test op of the fuel pump also.

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