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1995 gmc sonoma engine backfires

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Aug 3, 2014, 10:06 AM

Post #1 of 5 (1676 views)
post icon 1995 gmc sonoma engine backfires Sign In

I have a 1995 gmc sonoma 4.3 v6 vortec 2wd with a little over 300000 miles on it. 3 wks ago going on 4 i replaced both of my head gaskets and ever since i have been unable to get my truck running like it should. since then ive also replaced the plugs plug wires rotor timing chain cam and crank sprockets intake manifold gaskets and distributor cap and its still backfiring on me. I dont have the money to take it to get it fixed and i cant get anyone to help me of any great degree.they tell me its the timing and ive checked it and rechecked it and its right where it needs to be. Im at a loss as to.what more i can do and honestly im about to start pulling my hair out. smart alec comments wont be tollerated. i cant just go out and get another vehicle not till i find steady work. PLEASE SOMEBODY HELP ME WITH MY NIGHTMARE OF A TRUCK!

(This post was edited by blyons81 on Aug 3, 2014, 10:19 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 3, 2014, 10:19 AM

Post #2 of 5 (1668 views)
Re: 1995 gmc sonoma engine backfires Sign In

"Vortec" I don't think you can adjust your own timing at all like older engines on this so have to have just that done or get the equipment not known right now by me for especially model year 1995? Others are not adjustable the next model year anyway and can't look it up right now. If everything else is OK that's the trouble most likely and don't wait as it's harming the engine,


(This post was edited by Tom Greenleaf on Aug 3, 2014, 10:22 AM)

kev2 profile image

Aug 3, 2014, 1:11 PM

Post #3 of 5 (1651 views)
Re: 1995 gmc sonoma engine backfires Sign In

tom is correct you cannot adjust the timing -

SO do you have a scanner- first we will need the codes- then to set the CMP CKP correlation, AKA sync.
Let us know about 1) scanner 2) codes 3) and maybe how you set the CMP when reinstalling the dist.

Hammer Time
Ultimate Carjunky / Moderator
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Aug 3, 2014, 4:01 PM

Post #4 of 5 (1645 views)
Re: 1995 gmc sonoma engine backfires Sign In

I'll be really shocked if this engine even survives this job with that many miles on it. The lower end just can't handle the increase on compression and I'm sure the heads weren't in very good shape in the first place.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Ultimate Carjunky / Moderator
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Aug 3, 2014, 5:29 PM

Post #5 of 5 (1640 views)
Re: 1995 gmc sonoma engine backfires Sign In

Does it backfire while cranking, idling, and/or under heavy load?

Is the engine missing or lacking power? Is the check engine light on?

Did you send the heads off to a machine shop? HT is right that the bottom end is probably worn out with that many miles on it. Did it smoke or have low compression before you took it apart? Why did you take it apart?

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 3, 2014, 5:31 PM)

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