Hi Frans,
We had a problem with vapor lock in our XS mono-wheel with 912S, which caused
the
engine to run rough. I happened several times, only in the winter months.
This happened several times on take off after a cold start of the engine, at
or near sea level. We use auto fuel, and here in the US, they put more
volatiles
in the fuel in the cold months to help starting. It seemed to create a bubble
of vapor at or near the carbs that would slowly (tens of minutes) go away.
On one occasion I was doing some glide tests (at about 8000 feet) with the
engine shut down, when I restarted the engine it ran rough, I turned on the
electric
boost pump and it killed the engine completely. What I think happened
is the extra boost 'blew' the entire bubble into the carbs all at once and
killed
the engine. I restarted the engine and it ran better in a few minutes.
We put aluminum coated insulation around the float bowls and nearby lines and
never
had the problem again.
Regards,
Terry Seaver
A135 XS
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Frans Veldman
Sent: Monday, July 30, 2012 8:06 AM
Subject: Re: Europa-List: Vapour lock? Why?
Jeff,
> My own experience with vapor lock was nerve wracking. After fighting it
> for months, I finally figured it out. The carb bowls were getting hot.
This is not the problem I have. The engine was still relatively cold,
and I saw the fuel pressure drop. The fuel pressure is measured before
the carbs. A vapor lock inside the carbs doesn't result in a pressure
drop before the carbs.
I also got some private mails, but not everyone seems to know that I
have a Rotax 914. The 914 has two electrical pumps, mounted under the
bagage bay. If there is a fuel pressure drop, something is wrong outside
of the engine bay (unless it is the fuel pressure regulator itself).
I appreciate your advice, but I don't think it applies to my ship. It
can't have been the carbs.
Frans
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