1979 camaro sputters dies on accelaration


Old 04-21-08, 05:01 AM
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Question 1979 camaro sputters dies on accelaration

My 1979 camaro Z28 with 350 V8 / 4 barrell edlebrock idles fine for about 25 seconds and then will sometimes die.
It will always sputter/die as soon as you begin to accelerate. both in neutral and on the road. Once you get it passed the initial acceleration, it evens out and sounds great for a little while then it will inevitabley begin to trip and sputter. When driving - sometimes it will just simply die. it restarts easy though. On the road, at higher rpms, it begins to backfire and run horribly - ussually dieing.
I have replaced the module (distibutor)
distributor cap and rotor
I have also tried to adjust the time by rotating the distributor. as would be expected the engine runs "normal" to rough depending on rotation. but the same characteristics listed above are present.
Any help would be greatly appreciated. I am going to have to stop shaving my head just so I can pull out my hair
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Old 04-21-08, 05:27 AM
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make sure the EGR valve isn't stuck open or connected wrong...are you getting any black smoke? try looking down the throat of the carb while it idles (don't rev the engine while you're doing this) and see if you see fuel dripping inside off of the venturi. it may be time for a carb overhaul...and your description sounds like the carb is "loading up"...the technical term for "way too rich" if it's dripping internally, it needs rebuilt.
Old 04-21-08, 06:21 AM
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thanks for the quick reply and suggestions.

to answer your question, there is no black smoke.
it's seems so strange that all of this stuff is happening at once -
distributor problem and now a carb problem.

If there is no problem with the rpg valve and i don't see any the gas dripping from the venturi...
what would be next on the list to check? thanks again!
Old 04-21-08, 06:04 PM
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Had you been doing anything under the hood just before all this happened? Nice to be able to rule out vacuum line being left off, rearranged, or whatever.

Not that anything I say is the cause, and we welcome those who can hone in the actual cause - but without knowing, I'd look at easy stuff. I'd check vacuum lines. Make sure air filter good. Make sure gas cap does not make a whoosh sound when removed, after you run the car and it starts stumbling. That no rubber fuel line is collapsing. Make sure throttle plates open in proper sequence for conditions. Check the spark advance curve to make sure nothing out of the ordinary there. Make sure no arcing from wires under the hood at night. Make sure PCV works. Possibly pull plugs to see if one particular cylinder seems to be picked on. Make sure fuel filter good. Then onto fuel delivery - and that accelerator pump puts out nice squirt. Things fairly quick to check, without arguing and saying that some of these wouldn't be the cause.
Old 04-21-08, 06:12 PM
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Not a pro on carbs, but could it be the accelerator pump on the carb? Would have been my diagnosis on my 55 Chevy back in the 60's.
Old 04-21-08, 08:29 PM
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sounds a lot like an accel pump to me also. But I would also check for vac leaks by running propane out of a torch that is not lit around the carb and intake. I like to use a small dia vac hose with a 1 ft section of brake line in the end to get in tight to small spaces. if the eng speeds up you have a vac leak. The nice thing about propane is it doesn't leave a residue on the engine. Also if you plug the pcv valve and run the propane into the valve cover it could tell you if you have a internal vac leak due to warped intake. I used to see that on about that year chev with the factory aluminum intakes.
The back fireing sometimes can be a cam that is starting to go flat to check that you would need to pull valve covers and measure the lift of each pushrod. In 1982 chev had a bunch of cams go bad due to poor heat treating. but age will also eventully get them all. also check for excessive back pressure from the exhaust, just drop the exhaust at the headers and run for a few minutes to check that out.

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