Fuel is boiling - Team Camaro Tech
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post #1 of 7 (permalink) Old May 8th, 09, 08:03 AM Thread Starter
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Woody
 
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Fuel is boiling

I have a 350 with a Holley mechanical fuel pump which normally gives about 6 pounds of fuel pressure and a Holley 650. The problem is once the engine reaches operating temp., the fuel is boiling in the carburator and causes the engine to stall. I tried re-routing the fuel line away from any heat sources, but no luck. Any suggestions would be greatly appreciated.
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post #2 of 7 (permalink) Old May 8th, 09, 09:03 AM
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Harry
 
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Re: Fuel is boiling

Hey WOODY a phenolic carb spacer will fix your problem!
heat soak from intake is the culprit.
either wood or plastic
stay away from aliminum carb spacers


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post #3 of 7 (permalink) Old May 8th, 09, 09:13 AM
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Re: Fuel is boiling

Is the intake stock or aftermarket? If stock does it have the exhaust crossover passage? If it has the passage, do the intake gaskets have the block off plates installed?

Eric
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post #4 of 7 (permalink) Old May 8th, 09, 10:08 AM Thread Starter
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Woody
 
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Re: Fuel is boiling

The exhaust port wasn't blocked off, I got no carb spacer or intake heat shield and it's an Edelbrock intake. I think I might realize what the problems are now!!
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post #5 of 7 (permalink) Old May 11th, 09, 05:55 PM
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Re: Fuel is boiling

Those are two good ideas-

* phenolic carb spacer
* exhaust crossover heat block-offs

I think if you do those two things, your problem will go away.......

-

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #6 of 7 (permalink) Old May 25th, 09, 12:04 PM Thread Starter
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Woody
 
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Re: Fuel is boiling

I have put on Felpro intake gaskets that have the exhaust ports blocked off. I have added a Holley heat shield as well as a phenolic spacer. I reduced the fuel pressure down to 4 psi. I made sure the float bowl wasn't loading up with fuel.
Fuel is still boiling!! I am already running a Holley electric fuel pump with regulator and return line.
Any other suggestions?? I'm at a total loss.

OK, I realized what was happening. After the engine and fuel pump were shut off, residual fuel pressure(which I assume was coming from the tank) continued to drip fuel down into the manifold. #8 cylinder was full and I couldn't even turn it over.
Removed fuel cap, pressure released. My "vented cap" will suck air in, but it doesn't seem to let it out. I found this out by blowing on the inside center of the cap and then sucking on it. Air seemed to flow freely in, but it was very difficult to get any to go out. I drilled a damn hole in it. I'll let you know if that works.

Last edited by bama_69; May 25th, 09 at 04:03 PM. Reason: Additional Info
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post #7 of 7 (permalink) Old May 26th, 09, 12:29 PM
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Re: Fuel is boiling

A vented cap is only vented one way in most conditions. It allows the tank to remain at atmospheric pressure while the fuel is drawn through the system which keeps the tank from collapsing or fuel pump failure. It functions as a check valve to keep vapors from escaping and letting your fuel evaporate. It should only vent to atmosphere at a certain pressure.

Bet it felt good drilling a hole in it anyway.

I do remember reading about someone solving a hot start problem on a 3x2 big block Corvette by drilling a small hole in the gas cap though.....

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Last edited by Steiner; May 26th, 09 at 12:44 PM.
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