Vapor lock question

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
pvtcook
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Re: Vapor lock question

Post by pvtcook » Mon Jun 06, 2011 3:02 pm

Wow thanks for all the info. Ive got alot of things to check I appreciate it.
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Re: Vapor lock question

Post by tamnalan » Mon Jun 06, 2011 6:04 pm

41jeeps wrote:I would first check if it does not flood after shut down.
Many jeeps suffer from leaky floater needles and flood a few minutes after shut down.
Mine does exactly this. If I immediately pop the hood when I turn the motor off and let things cool for a few minutes, then it won't flood.

So what's the solution? New needle? I don't think it's a dirt problem.
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Re: Vapor lock question

Post by artificer » Mon Jun 06, 2011 9:05 pm

Alan offered: So what's the solution? New needle? I don't think it's a dirt problem.
Anti percolation valve which this carb may not have? or lower the fuel pressure back to specification ....check with your vacuum/pressure gauge, plus check & adjust the float height.
Fuel & carb act as a heat sink & guess what happens?
Expansion perhaps boiling then discharge into the inlet manifold; needle valve opens so more fuel gets into the carb bowl all a progressive process that which contributes to flooding.
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Re: Vapor lock question

Post by Joe Gopan » Tue Jun 07, 2011 4:51 am

Add Hi Test on hot days.
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Milo 42 GPW
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Re: Vapor lock question

Post by Milo 42 GPW » Wed Jun 08, 2011 4:04 pm

My jeep did this also and it was that the timing was way off. The carb would get overheated and boil out the fuel when stopped at a long red light and then die when I tried to accelerate at the green light. When I corrected the timing my "vapor lock" went away.
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Re: Vapor lock question

Post by Joe Gopan » Thu Jun 09, 2011 2:21 am

The original MB/GPW design anticipated vapor lock and incorporated a pressure cap to counteract the tendency to vapor lock.
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Re: Vapor lock question

Post by David V » Thu Jun 09, 2011 12:56 pm

This topic has come up again and again. You should check some of the other posts on it.
Personally it has only happened once to me - and it was very hot that day on black tarmac. So the jeep stopped running at the lights. 5 minutes cooling down and off she went.
My solution was to add a thermal sleeve (Summet Racing) on the fuel line at that area.
It hasn't happened again.
I really don't think this occasional problem merits changing the fuel pump.
Other people have put pegs on the fuel line to dissipate the heat.
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Re: Vapor lock question

Post by Joe Gopan » Thu Jun 09, 2011 2:21 pm

Sooner or later everyone will experience vapor lock, it is not a serious symptom and it is only temporary, experience and familiarity with your own vehicles starting habits will allou you to recognize and overcome it. Today's lead free alcohol based fuel lends somewhat to the problem, not every tankful acts the same at times.
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