Vapor Lock - Jul 2003

I talked to a test pilot named Bill Mitchell in Denver. He immediately
said "vapor lock" which was indeed my first reaction to this. The
erratic symptoms fit my description of behavior. He suggested that I
aggrevate the problem by using auto high-test unleaded gas and that I
should go to 100LL

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Date:         Thu, 17 Jul 2003 10:58:16 -0600
Reply-To:     Ximango Owners Group <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       Ximango Owners Group <XIMANGO@HOME.EASE.LSOFT.COM>
From:         William Cotton <cotton@ATMOS.COLOSTATE.EDU>
Subject:      Vapor Lock
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I sent an e-mail out last week about problems with erratic engine
sputtering on take-off. The first encounter was on a day with temp's at
95F at FNL which is at 5000'MSL. I have experienced it several times
since but can't reproduce it sitting on the ground running it up.

 I changed the plugs which showed carbon build up suggesting it was
running rich. But, this shouldn't produce erratic behavior.

 I talked to a test pilot named Bill Mitchell in Denver. He immediately
said "vapor lock" which was indeed my first reaction to this. The
erratic symptoms fit my description of behavior. He suggested that I
aggrevate the problem by using auto high-test unleaded gas and that I
should go to 100LL. Auto gas is more likely to vaporize than 100LL. The
problem occurs when the engine is run at low RPM for extended periods
over hot tarmac. Since we have a 7000' runway this is certainly the case
as I taxi at 2000RPM.

  There are two fixes. One of course, going to 100LL. The other is put
in a fuel return to the tank from as close to the engine as possible.

Any comments suggestions? Bill Cotton
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Date:         Thu, 17 Jul 2003 17:31:03 -0600
Reply-To:     Ximango Owners Group <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       Ximango Owners Group <XIMANGO@HOME.EASE.LSOFT.COM>
From:         "jim.durango" <jim.durango@STARBAND.NET>
Subject:      Re: Vapor Lock
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Hi,

Maybe vapor lock but I have not experienced that using autogas at take-off
density altitudes above 11,000 feet.

Jim McCann