1988 Buick Regal Running to rich

Tiny
AMS175045
  • MEMBER
  • 1988 BUICK REGAL
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 200,000 MILES
Problem - Car is running very rich, no smoke but strong order of fuel at tail pipe. Loss of power, car shakes at 40 mph or 1900 - 2000 rpm. It came on quickly.

Tested fuel pressure before rail (43) at fuel rail (38) and stays there while running. Checked idle control TPS both seem to be fine.

I have replaced the fuel pressure regulator, cleaned all injectors and replaced all seals, plan to change all plugs in the a.M.

Question is what else may cause such a problem as this? I don't think it is pump or filter related because of the pressure reading from the test.

Can you help with this one?
Thursday, March 5th, 2009 AT 8:39 PM

3 Replies

Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
With 200K on the old girl, she must be pretty well taken care of. First thing that comes to mind as I read your post was the map sensor. If there is the slightest leak in the vacuum line going to it you have a rich condition. The leak may throw the sensor out of range, but not enough to trip a check engine light in the ECM. Also, in the past, I've seen these MAPs go bad to the point where they flood the engine out, and still not trip a code for MAP sensor. Hope this helps.
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Thursday, March 5th, 2009 AT 10:32 PM
Tiny
AMS175045
  • MEMBER
  • 2 POSTS
Thanks it does help. If what I'm doing now doesn't work, then I'll test it nest.
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Friday, March 6th, 2009 AT 12:33 AM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Complete
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Saturday, March 21st, 2009 AT 8:31 PM

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