Hard to Start When Hot - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 17 (permalink) Old May 22nd, 04, 12:08 PM Thread Starter
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My '67 Camaro (350, Edelbrok Q-Jet) starts fine
when cold and runs well @ 180 F. After shut down
(when hot) for 10 minutes or so its a bitch to
start. The only way to start is by flooring the
gas pedal. Sometimes it'll backfire when doing so.
The backfire is really bothering me. It'll also
backfire sometimes when I kick in the 4BBl.
Had this car for 20 years and never had this problem. Any suggestions?
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post #2 of 17 (permalink) Old May 22nd, 04, 01:40 PM
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sounds like the power valve is blown in the carb.
also the carb might be getting too hot.
try a insulating spacer between the carb and intake.


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post #3 of 17 (permalink) Old May 22nd, 04, 02:13 PM Thread Starter
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Have had a GM carb heat shield a few years now, which worked out well. The Edelbrok Q-Jet, on the other hand, is just one season old so it is suspect. Power valve, eh? And I thought only vintage
Holly's had problems with blown power valves.
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post #4 of 17 (permalink) Old May 22nd, 04, 05:50 PM
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sounds like the carb is leaking fuel into intake somehow. seems to me they had problems with leaky bowl plugs. engine stopped,let sit hot, then open up throttle plates & look into carb, I'll bet u'll see gas
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post #5 of 17 (permalink) Old May 26th, 04, 11:46 AM
 
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Heat soak? I get the same problem when the car gets hot. No back firing, no excessive gas smell, just has a hard time to start. I attribute the problem to the headers being way to close to the starter and my lack of a heat shield of some sort. Just my .02
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post #6 of 17 (permalink) Old May 29th, 04, 12:54 PM Thread Starter
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"engine stopped,let sit hot, then open up throttle plates & look into carb, I'll bet u'll see gas"

There was a small puddle of gas (1/2" diameter)
below one primary bore. Nothing unusual? The
problem may be that I'm running 89 octane, rather
than the usual 92.
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post #7 of 17 (permalink) Old May 29th, 04, 01:57 PM
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I would guess heat soak. Just curious; is the Edelbrock carb aluminum? If so, might just suck up heat a little faster than your old carb. Might try a phenolic spacer. I used that and a remote solenoid to solve the heat soak problem on mine. [img]graemlins/thumbsup.gif[/img]

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post #8 of 17 (permalink) Old Jun 30th, 04, 06:12 AM
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I've lived with this exact same problem for over a year since installing an Edelbrock Performer manifold and 600cfm carb on my stock 327. I've tried everything. Heat insulator, checked and double-checked float levels, installed fuel pressure regulator. Nothing has worked. Edelbrock techs can't figure it out either.
If anyone has ANY new ideas, please let us know. It's not an earth-shattering problem, but it is very annoying.
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post #9 of 17 (permalink) Old Jun 30th, 04, 06:35 AM
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I had similar issues and found the wires to my starter to close to the block in back, and even warped and melted a little too. I intalled one of those tubes that bolts near the starter and the wires run thru it before attaching to the starter elec. connections. Since I did that, no problems. The heat that affects the starter and causes it to stiffen up, can also affect the wires, causing heavier than normal load on them. Just an idea.
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post #10 of 17 (permalink) Old Jun 30th, 04, 10:44 AM
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Thanks for the reply, Click. Actually, my starter turns over just fine. It acts more like the engine is flooded. You have to hold the pedal down halfway or all the way, and even then it takes awhile to start.

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post #11 of 17 (permalink) Old Jul 2nd, 04, 02:10 PM
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Convert-
Sounds like your flooding out due to carb boil. Toss in a thermoplate and see if the problem goes away..

Have you noticed any engine runnon?

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post #12 of 17 (permalink) Old Jul 4th, 04, 05:57 AM
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try a different carb?


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post #13 of 17 (permalink) Old Jul 5th, 04, 05:39 AM
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What about your choke? Chokes can cause this. Here is one example how. If the carb is jetted lean and the choke is applying too much it will start fine cold and have trouble when hot. The opposite is also possible, if the carb is jetted too rich and the choke isn't applying at all, then it wills start fine cold and flood when hot.

Whenever you sense a flood condition, put the accellerator pedal to the floor and hold it there while cranking until it starts. This will clear the flood condition. At least that should get you going again and perhaps shed light on the problem.

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post #14 of 17 (permalink) Old Jul 7th, 04, 12:24 PM Thread Starter
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I don't believe it's flooding cause it'll
fire immediately if I pump the gas pedal a few
times prior to turning it over. It'll get
realy close to starting but immediately conk
out. The only sure way to start is by pumping
it a few times, then hold the pedal to the
floor. Also, I looked into the manifold and
saw no gas puddles after it sat hot.
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post #15 of 17 (permalink) Old Jul 8th, 04, 07:05 AM
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Hmmm....

What I used to do with my QJets is remove them and fill the bowl with gas (if they were dry). Then set the carb on a piece of paper and let it sit there for a while (even overnight) to see if fuel was seeping though the well plugs. If so I would epoxy the plugs and repeat until they didn't leak.

Could the choke be your problem? Is it closed during hot start? If you have to floor it to start that would imply that the mixture was too rich either too much fuel (leaky plugs) or not enough air (choke valve not open enough).


That's all I can think of assuming that the carb is for sure the problem.

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