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post #2 of (permalink) Old 03-18-2002, 06:05 PM
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Re: Diesel fuel for vapor lock

If you were in Nebraska last week, I really doubt that vapor lock was your problem. And if it was vapor lock, I don't think much of the diesel trick. It might help vapor lock, but will also lower the effective octane of the gas, and do bad things to the plugs, besides making the carb meter improperly.

Vapor lock is caused by fuel boiling in the pump and the supply line before the pump. The valves in the pump won't stop the vapor, so the pump quits pumping. The best cure for vapor lock is a return line to the tank, so that a continuous flow of cool fuel is passing through the pump.

I think your Jeep should have had this from the factory. If it didn't, look at a later model and copy what's there.

That's if you really have a vapor lock problem. I think something else is wrong, because your p[rofile doesn't mention any engine modifications. A stock engine shouldn't create so much heat under the hood that gasoline is boiling in March.

A clogged pickup could cause the pump to suck so hard that the pressure drop causes the fuel to boil in the line. That would be one thing to check if it is behaving like a classic vapor lock problem.
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