1999 GMC Jimmy

Tiny
RICKINMPLS
  • MEMBER
  • 1999 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Generally the car runs good, but at times the car will not start after it has sat for awhile, it is very difficult to start, it backfires and runs very bad. Then after time it runs fine. I had the code checked PO300 random misfiring. Yesterday it did not start for several hours then it easily started and ran fine. What could this be?
Monday, January 19th, 2009 AT 11:04 AM

2 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Hi, if you have the spider fuel system, I'd check that first. These type fuel systems are known for problems. Fuel pressure is critical, the poppets stick and there can be leaking problems. I'd check fuel pressure, you need a gage for that. If it has been awhile since you changed the fuel filter, even if it isn't causing a problem, that's a maintenance issue. If you change the fuel filter, just make sure there is no pressure on the system before you take any lines loose.

If you think it might be a poppet sticking, you might try some seafoam. I don't know if that will help or not, some people says it does.
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Monday, January 19th, 2009 AT 11:20 AM
Tiny
RICKINMPLS
  • MEMBER
  • 2 POSTS
Thank you for the information
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Monday, January 19th, 2009 AT 11:30 AM

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