95 K1500 bucking hard and backfiring
Asked by Earland Jul 02, 2018 at 05:01 PM about the 1995 Chevrolet C/K 1500 Cheyenne Extended Cab 4WD
Question type: Maintenance & Repair
So this truck sat for 4 yrs. Had a used trans and
transfer case put in a couple months ago. It has
since developed a very hard buck while driving that
has progressively gotten worse. Im afraid engine
damage is imminent. The bucking is random.
Doesnt feel mechanical, like the trans. It feels
ignition related. At first i thought it was fuel pump.
Having owned several chevys i know what that
pump feels like when it cuts out. As it got worse
ive leaned more towards ignition. It backfires pretty
bad while it bucks along. I can feel the backfire
under my feet. It feels like the ignition is just
cutting out repeatedlu when it happens and makes
the truck just buck and stumble along. Happens at
any speed but mainly under load, at high gears,
tach at 2k. Or during acceleration from a stop or
getting onto highway. I threw a tps in. No change.
Temp gauge never goes over 110. Threw a CTS
(cylinder head). Hasnt done anything. Trans went
into failsafe and tach went nuts a couple weeks
ago. Replaced ignition switch and fixed that, but
the bucking has since gotten worse. Im kinda
stuck now and not sure what to check.
12 Answers
Would bad timing have such random symptoms though. Usually bad timing equates to constant poor performance, lack of power, poor starting..
When it does start bucking i can let off gas, or push it to the floor and muscle through it
If it were out of time, it would run like crap all the time, not an occasional hiccup. Need to run a scan on it. Sounds like a throttle position sensor.
Good do that, also check you distributor cap,rotor and wires unless you replaced them already? also check the ignition module for any burn marks.
Replace the spark plugs too, I forgot.
Also, to add: when making turns it tries to stall. Moreso on right hand turns when the load is higher
Your throttle body butterfly might not be operating smoothly, or you could even have a vacuum line off or cracked, throwing off the computer. I believe it's fly-by-wire (electrically operated)
