1988 GMC S15 Engine Backfires at middle RPM under load

Tiny
FAYE C
  • MEMBER
  • 1988 GMC S15
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 160,192 MILES
The engine backfires through the TBI blowing the vacume hoses off the TBI asnd loses power. Runs fine at idle, low speed, and high speed if you can get past the mid point. This occurs within 2 miles or so.
I have Inspected and changed Vacume hoses.
Tried 2 coils
Changed out distributor.
Changed computer chip.
Changed spark module.
New fuel filter and gas.
Removed exhaust.

HELP PLEASE
Friday, September 4th, 2009 AT 8:15 AM

1 Reply

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok so have you checked the tps? Have you check the map sensor? Have you checked the fuel pressure? Have you checked the timing? Have you checked for timing chain slack? Get back to me with what you have checked and we will go from there.
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Friday, September 4th, 2009 AT 10:23 AM

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