Stalls and Bucks

[dckingan]

Problem - Engines starts and idles nicely 650-700 rpm. After warming up it will sometimes stall when coming down to idle at a light or sign. It will restart but goes crazy running 2500-3000 rpm until it recovers and comes back down to a normal idle. Also when decellerating with foot off the gas pedal and reaccellerating it hesitates and bucks like the engine had stalled and restarted. I have checked and repaired all vaccum leaks, rebuilt all the injectors without success. It does appear the idle screw has been tampered with, if there was a plug on the adjustment screw it is gone now. Any suggestions would be greatly appreaciated.

Thanks in advance,
Dennis

[gbrtng]

Any SES light? If so, read the code(s) and report back.

[sammy]

you might want to do a fuel pump ck , sounds like what my 90 did a while back .it was the primary fuel pump starting to go out .

[dckingan]

Thanks gbrtng,

No SES light but will check for codes in case light is not working correctly. SES does come on and go out after starting. Car is currently in hibernation but want to put together a "to do list" with your and others ideas when the weather warms up.

Dennis

[dckingan]

Thanks sammy,

Will check out fuel pumps when car comes out of hibernation.

Dennis

[tomtom72]

Hi Dennis, pull the Fuel Pressure regulator line and see if there is gas in it...that's the down & dirty diagnostic that may give you a fast answer. You could also do the KOEO fuel pump test in the garage just to see what the pumps are putting out. The test is in section 6 of the FSM. I know on my 90 I replaces my pumps just because they were 18 yrs old.

May I ask who rebuilt your injectors? Usually our GM injectors don't respond well, specially the 90 & 91 injectors, to rebuild attempts.

Tom