1988 Buick Regal Running to rich

1988 BUICK REGAL
200,000 MILES • 6 CYL • FWD • AUTOMATIC
Avatar
AMS175045
  • MEMBER
  • 2 POSTS
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?
Mar 5, 2009 at 8:39 PM
Advertisement
Avatar
JAMES W.
  • CERTIFIED EXPERT
  • 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.
Mar 5, 2009 at 10:32 PM
Avatar
AMS175045
  • MEMBER
  • 2 POSTS
Thanks it does help. If what I'm doing now doesn't work, then I'll test it nest.
Mar 6, 2009 at 12:33 AM
Advertisement
Avatar
JAMES W.
  • CERTIFIED EXPERT
  • 2,394 POSTS
Complete
Mar 21, 2009 at 8:31 PM