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Fuel Pressure Problem 1997 Chevy C1500

impalassondubs

By impalassondubs
in Ask A GM Technician

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impalassondubs Enthusiast

impalassondubs

Posted
Posted

well im new to this forum so thanks in advance!!!

 

 

i have a 1997 chevy c1500 2wd 5.7L 350. lately i have been having a problem starting

from time to time. the engine is newly tuned up so no ignition problems are expected. fuel pump and sock is only a year old. i did a fuel pressure test and when i turn the key in the on postion, i hear the fuel pump come on like its supposed to, however it only reads 50psi til the pump stops. then the pressure goes down to 20psi and holds. with some doing, i can get it running and the gauge reads 50psi steady. is there a problem here?? is the pressure supposed to drop when the pump stops? i thought it was supposed to hold steady..... manufacture suggested fuel pressure is 60-66psi. while driving the truck at low rmps it drives great. upon heavy excelleration it hesitates bad and pops and bucks....

 

any ideas???

 

thanks

 

shilo edgar

fl

 

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ss502gmc Enthusiast

ss502gmc

Posted
Posted
well im new to this forum so thanks in advance!!!

 

 

i have a 1997 chevy c1500 2wd 5.7L 350. lately i have been having a problem starting

from time to time. the engine is newly tuned up so no ignition problems are expected. fuel pump and sock is only a year old. i did a fuel pressure test and when i turn the key in the on postion, i hear the fuel pump come on like its supposed to, however it only reads 50psi til the pump stops. then the pressure goes down to 20psi and holds. with some doing, i can get it running and the gauge reads 50psi steady. is there a problem here?? is the pressure supposed to drop when the pump stops? i thought it was supposed to hold steady..... manufacture suggested fuel pressure is 60-66psi. while driving the truck at low rmps it drives great. upon heavy excelleration it hesitates bad and pops and bucks....

 

any ideas???

 

thanks

 

shilo edgar

fl

fuel filter change??

 

[email protected]

impalassondubs Enthusiast

impalassondubs

Posted
  • Author
Posted

Sounds like the pump is heading south. I have seen them go bad in a years time.

 

 

 

re: could it be the fuel pressure regulator or injector assembly?

 

of course the year warranty that came with the pump is past. i dont wanna just throw parts at it hoping!!

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Take the fuel filter off & try to blow through it in direction of fuel flow ...... any resistance at all, change it.

txab Senior Enthusiast

txab

Posted
Posted

Check filter.

 

Pressure should be 55-62 minimum according to GM. Probably pump, pressure regulator

impalassondubs Enthusiast

impalassondubs

Posted
  • Author
Posted

i did another fuel pressure test, KOEO, this time with the return fuel line blocked off. my pressure went to 55psi til the pump stopped and then still dropped to 20psi. does that tell me its not the pump???

 

 

anyone??

 

thanks!!

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
i did another fuel pressure test, KOEO, this time with the return fuel line blocked off. my pressure went to 55psi til the pump stopped and then still dropped to 20psi. does that tell me its not the pump???

 

 

anyone??

 

thanks!!

If there are no obvious leaks anywhere...than this tells you it is in fact the pump...the fuel is bleeding back through and in turn venting pressure back in the tank.

 

Now have you done this with the air breather off to ensure it wasn't an injector leaking down.

 

Search the truck for leaks too.

 

My guess with this though is that it would be the pump...line pressure should hold steady if it has no where to go.

 

Having said that I would buy pressure regulator too. I would install it first as regulators sometimes leak internally....and besides...if your putting a new pump on...you may as well have a new regulator too. If the stock one is on there its probably not far from going anyway...and they're cheap anyway.

rodram Enthusiast

rodram

Posted
Posted

... you need a NEW FUEL PUMP .... no question that this will fix the problem ....

 

.. if you still have a warranty on your 1 year old pump... then get it replaced on warranty

 

.. otherwise go to a dealer and buy a ACDelco pump or to NAPA (or similar store) and buy a Delphi brand pump

 

.. Airtex pumps are know to be far less reliable than the OE pumps (ACDelco or Delphi)... don't buy a fuel pump off ebay (there are too many counterfeit-brand stuff on there and for a fuel pump you can't take the risk....

  • 11 months later...
gandl2123 New Member

gandl2123

Posted
Posted
no its direct replacement. you unplug one and plug in the new one

 

Having same problem with 97 C1500 base 4.3L. Starts great, runs at idle...put in gear and sputters and backfires through cat. Was 56 psi at schrader valve. Was going to change pump but pump was going from 0psi to 56 within 1-sec....whew, can't be pump. So before I spent 200. to 400. on a pump I took the upper plenum off and found that the fuel pressure regulator had gunk all over it and that the vacuum end that doesn't have a hose that connects to it....(guess it gets its vacuum being inside the plenum???) was all caked up with crud. I took it off and made sure the filter screen was clean and cleaned out that end of it that had crud in that little pipe end that points down. Wha-la 62psi. So, don't condemn the pump so fast.

 

Augusta, GA

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