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Jay, Chevy Mechanic
Category: Chevy
Satisfied Customers: 596
Experience:  Several yrs experience, GM Trained,
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2001 gmc sierra 1500: v8..check engine light..the truck starts acting

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I have a 2001 gmc sierra 1500 4.8liter v8 the check engine light keeps coming on. When it does the truck starts acting up {cuting out) when i give it gas. I have to pull over and turn it off. then it will start fine until i give it alot of gas. auto zone checked out the check engine light and told me it was an oxygen sensor so i changed it. Then they rest the light about 1 day later it came on again they said it was geting low voltage to the sensor. I fixed it and the light still keeps coming on. I can reset the light and it runs fine but as soon as the light comes back on it runs like crap. can you tell me what is wrong and how to fix it. They didnt give me a code. Thank you
HelloCustomer it would help a lot if you were able to get the code. Without it were doing a lot of guess work.
Customer: replied 7 years ago.
i got two codes from autozone today there are po171 and po174 the told me that i wasnt getting enough fuel that it could be a vacumm leak or a bad fuel pump could you tell me which one it could most likely be and how to fix it. thank you

HelloCustomer I'm thinking it is likely more likely to be the fuel pump since both sides of the engine are producing lean but I think it is still worthwhile to check for a vacuum leak. Here are some things to do:

  1. Operate the engine at idle.

Check for vacuum leaks at the intake manifold, throttle body, and injector O-rings.

  1. Check the air induction system and the air intake ducts for leaks.
  2. Check the AIR system for leaks, improper air delivery, and for the shut-off valves not closing.
  3. Check the crankcase ventilation system for leaks.

Basically if you notice your engine running a little bit of a high idle or rough idle it could be a vacuum leak and reply back to me if this is the problem. If you do not find anything in the vacuum area it likely needs a fuel pump, this requires removing the fuel tank underneath the car. This is quite a task without a hoist to lift the truck up and without a special jack to rest the tank on but if you would like the instructions on how to remove the tank, I can provide it to you.

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