Rough running while in gear


Asked by Jan 19, 2014 at 05:57 PM about the 1990 GMC Vandura G35

Question type: Maintenance & Repair

Hi John.. I have read the past with
dragonfly at the top here.. I'm experiencing
these same problems as him. . But I don't
have. Or can find this gm inline fuel
pressure tester. .I can however tell you that
when I cleaned out the throttle body it ran
smooth and i could Rev it up with no rough
idle or bog..i stop spraying and it bogs
stalls or back fires out the throttle
body.flames as well  .. I have done the other
checks you discussed. Changed rotor cap
plugs wires  . vacumn line. cleaned egr
valve haven't done the pcv valve.. Going to
change the fuel filter today. . My question is
about the idle smooth while spraying ..
1989 gmc vandura 2500 v8 305

3 Answers


Sounds like an overly lean (not enough fuel) condition. Check for vacuum leaks, faulty fuel injectors, or bad fuel pressure regulator. HTH. -Jim

1 people found this helpful.

I changed fuel filter today it runs at idle fine now but in gear it feel like it misfire or something just not right still and back fires. . Checked the fuel injectors. They are spraying dome like spray each side


Thanks Jim.. How will i know if the regulator is faulty

2 people found this helpful.

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