Author Topic: Help in diagnosis  (Read 970 times)

camaro jock

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Help in diagnosis
« on: June 26, 2014, 05:10:11 PM »
I need a little assistance just got my Camaro out for the year and it starts and runs great til it warms up and it coughs and sputters bad. Could this be a faulty fuel pump? Car has 396 with quadrajet  I always like to look at carb last but acts like a carb problem, any ideas would be greatly appreciated. Thanks Darrell

cook_dw

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Re: Help in diagnosis
« Reply #1 on: June 26, 2014, 06:52:43 PM »
Make sure the choke is coming off and not sticking closed.
Darrell Cook
1967 LeMans Blue SS/RS L35 clone
1968 Rallye Green SS L78 - unrestored original
1968 Matador Red Z28

camaro jock

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Re: Help in diagnosis
« Reply #2 on: June 26, 2014, 07:46:41 PM »
Thanks, could that be in choke box? It looks like it does not open all the way, should it be straight up or closed partially?  Darrell

cook_dw

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Re: Help in diagnosis
« Reply #3 on: June 26, 2014, 08:04:40 PM »
I cant remember 100% on a q-jet but I want to say it opens to about 2/3s the way.  It should only be open about a 1/4 inch when choke is on.  If memory serves me.
Darrell Cook
1967 LeMans Blue SS/RS L35 clone
1968 Rallye Green SS L78 - unrestored original
1968 Matador Red Z28

BULLITT65

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Re: Help in diagnosis
« Reply #4 on: June 26, 2014, 09:09:42 PM »
It would be easy to check if that is the issue, once it is warm, manually open the choke and see if it makes a difference. I agree with Darrell it does sound like a choke problem.
1969 garnet red Z/28 46k mile unrestored X77
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camaro jock

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Re: Help in diagnosis
« Reply #5 on: June 27, 2014, 01:38:46 AM »
Thanks I will try this weekend, Darrell

hotrod68

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Re: Help in diagnosis
« Reply #6 on: June 27, 2014, 06:56:11 AM »
  Easy enough. Once it warms up take the air cleaner lid off and see if the choke is open. Or start it up cold and see if the choke opens as it warms up. It could be the accelerator pump. This damned ethanol gas eats up rubber like Ms PacMan. Once things get warm and expand, the pump diaphragm could be letting gas slide by it, causing the stumble. On the electrical side, I've seen coils break down when warmed up and the symptoms are similiar. Hard to pin down, but when in doubt revert to the basics. It's likely something very simple. Good luck and hope this helps.
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
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camaro jock

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Re: Help in diagnosis
« Reply #7 on: June 27, 2014, 11:25:53 AM »
Was not thinking of the accelerator pump, that is a good idea, do you think  I could rule out the fuel pump? Thanks Darrell

BULLITT65

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Re: Help in diagnosis
« Reply #8 on: June 27, 2014, 01:20:26 PM »
I helped my friend with his 76 Corvette a couple years back, he had the same problem. After going through 6 different things, it ended up being the spark plugs. They were fine until they heated up, then they started missing.... go figure.
1969 garnet red Z/28 46k mile unrestored X77
Looking for 3192477 (front) spiral shocks 3192851 (rear) please
Looking for an original LOF soft ray windshield
Looking for original Delco side post negative battery cable part # 6297651AV

hotrod68

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Re: Help in diagnosis
« Reply #9 on: June 28, 2014, 04:59:39 AM »
  Probably not the fuel pump. Being mechanical it either works or it doesn't. But it wouldn't hurt to pull the dipstick and smell for gas. If the diaphragm is leaking it's going straight into the engine oil.
   Excellent suggestion, Bullitt. And if the choke was sticking, it'd load them up even more and make them foul.
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior