Intermittent engine sputtering and backfiring when accelerating?

GSILVA

MEMBER
1993 CHEVROLET CHEYENNE
4.3L
6 CYL
2WD
AUTOMATIC
175,000 MILES

My truck sputters and backfires sometimes when I try to accelerate, and other times I can accelerate with no problem. So far I have done the following, I have changed the ignition coil, plugs and wires, EGR valve, checked MAP sensor, cap and rotor button, new fuel pump and filter, cleaned fuel injectors, timing is dead on the mark. It idle rough I suspect that I have a burnt valve, what are your thoughts?

2 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

First, check to see if there are diagnostic trouble codes stored. Here is a link that explains how it's done. All you will need is a short jumper wire or even a paper clip.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Now, take a look through this link that discusses the causes of backfires. See if anything helps.

https://www.2carpros.com/articles/engine-backfires-while-running

Since you have a rough idle, it could be a vacuum leak. A lean fuel mixture due to a leak can cause this to happen as well.

Here is a link that explains how to locate a leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know if there are codes stored or if you find any vacuum leaks. make sure to check the intake manifold for possible vacuum leaks.

Take care,

Joe