1999 GMC Sierra Possible Fuel pump or fuel filter

Tiny
SIERRABOY
  • MEMBER
  • 1999 GMC SIERRA
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Once the engine has warmed up, the vehicle starts to run really rough and doesn't idle well when I stop. You have to keep giving it more gas to keep it running. It shakes as well. I have attempted putting new gas in the truck but that was not the problem.
Saturday, July 19th, 2008 AT 9:59 AM

1 Reply

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
Last tune up was?
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Saturday, July 19th, 2008 AT 10:02 AM

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