1995 GMC C2500 backfire and bucking while accelerating

Tiny
NODOBO
  • MEMBER
  • 1995 GMC C2500
  • V8
  • 4WD
  • AUTOMATIC
  • 267,588 MILES
I was traveling 70 mph and needed to accelerate, when I did the truch bucked and backfired. I let off and it ran fine. Tried it again and it was okay once and then did it repeatedly. Idles fine but when revved it sounds like I am pumping accelerater. Just got full tuneup.
Saturday, December 5th, 2009 AT 4:09 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Oxygen sensor
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
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Saturday, December 5th, 2009 AT 4:18 PM

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