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ALLTECH, ASE Master and L1, Gm,VW,European
Category: Chevy
Satisfied Customers: 660
Experience:  15+ years wrenching as a living, a hobby into a well paying career.
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I have a 98 silverado 5.7. I had fuel delivery problems so

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I have a 98 silverado 5.7. I had fuel delivery problems so i replaced my filter and my fuel pump. Then about 2-3 weeks later i had the same symptoms. Engine will turn over but wont start. My mechanic hooked up the computer and said that i am running really lean. His assumption was "fuel regulation control valve. Does that sound possible and if so, where is it? i need to fix this truck asap.
Hello, Jason in Walla Walla. The fuel pressure regulator is part of the Injector assy under plastic intake cover. How does the truck run at idle? What brand of pump was installed? Check engine light, codes?
Customer: replied 8 years ago.
i dont know all the specifics. The fuel pump was most likely a decent brand, my mechanic doesnt use crappy parts. Right now the truck wont get to idle. The last time it was running, it would sound fine at idle, then if you pushed the gas it would try to cut out, revving the engine was impossible. The check engine light has been on for a while and when my mechanic checked the codes, i believe he said that the o2 sensors reported it running lean. He checked the pressure and the fuel pump was doing its job.
The fuel pressure was? It may have had pressure, but volume? I have had to replace pumps within weeks of first repair. Delco pumps have been the best so far of all, Carter,and a few other Napa options have been the worst. Your mechanic should be able to actually see fuel pump current waveform to confirm pumps ability to pump. The other possibility would be stuck poppets in the injector assy. You would get misfire codes with that most often though. Mass air flow sensor or vacuum leaks in intake can also toss lean codes and poor running. Let me know if this helps, Jason
Customer: replied 8 years ago.
i dont remember the exact pressure, he said it was normal for my truck. I had been warned about the poppets by another owner of a 98 chevy. I was told that at about 120k miles i would have problems with the fuel delivery. I need to crank open the engine today and atleast attempt to fix this. Do you have any ideas on what i can do to test whether its the poppets or not, or will i just have to open it up and see? Also if you think that it is the poppets, what do they look like and where are they located. The truck has been sitting now for 2 months and it needs to either work or be gone asap.

You can test for the poppets being stuck, but you need a scantool and a fuel pressure guage, Scantool will power pump to the set pressure(55-65psi) and will open 1 injector at a time, if the pressure doesnt drop when one injector is powered up then poppet is stuck. If poppet is stuck then I strongly reccommend the update injector assy(complete unit) from napa or Gm. When one poppet failes the others arent far behind, the new style is a complete redesign and is much more long lived.

Customer: replied 8 years ago.
ok thanks for the advice. i dont have access to those tools, but i do have a shinny new air compressor so i'm going to start looking. I can usually see whats wrong even with my limited knowledge. One last thing, do you know about how much that complete assembly will cost me? Thanks again.

and also, when i sprayed some start fluid in the carb looking thing, the engine starts up and then slowly dies. This is the last thing i swear. =)
I beleive its around 4-450 thru napa? Gm maybe a liitle more. The individual poppets for the origional are 60-100$ PER. last time I saw. I dont get to see what we pay for alot of the stuff as the service writer handles that though. You could try and remove injector connector at center of intake and with a nine volt battery and some wire or 12v from the battery, trigger each injector your self, but would still need a fuel pressure guage and cyle the key after each injector test to actually confirm flow as the injector may click but not spray. The pins 16 of them 2 for each injector are lined up in two rows of 8 pins. I can find or dummy up a diagram if you think nothing else is wrong(vacuum leaks, or a dirty mass air flow sensor). Let me know, Jason.
Customer: replied 8 years ago.
That would be awesome, i am about to take it apart. I can easily try the battery test, so a diagram would really help. you mentioned a Mass Air Flow censor, where is that located so i can check that as well?


This is the diagram for the injectors. Airflow meter is located at airfilter connection to throttle tube. The PCM grounds each injector , the pins should be labled in tiny stampings on connector or harness (c105)

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