<VV> Vapor Lock

[Spencer Shepard]

I'm not an advocate of electric pumps in general but I appreciate the
necessity of avoiding vapor lock. When I traveled to the Chicago convention
in '87(?) I experienced vapor lock on my Greenbrier after it had a "hot
soak" while my family had lunch. It was about 100 degrees ambient and I
stopped for about 45 minutes after 4 hours at about 70MPH. Of course it
wouldn't start when we finished. I finally got it going by blowing into the
gas tank to pressurized it enough to get gas to the carbs. That kind of hard
to explain to a wife and 2 young kids.

When I got home I solved the problem by putting an electric pump  (square
type) just downstream from the gas tank. I didn't want one in the engine
compartment. I also didn't want one running all the time so I left the
mechanical pump in place and wired the electric one through  a switch I
mounted under the dash. That way I can turn the electric pump on when I need
it and don't have to worry about it being on when I don't need it. I used a
switch with a red light that is on when the switch is on so I know when the
pump is working. I can also hear it because it is so close to my feet..

I often don't drive it for months at a time and the electric pump is also
handy for getting it started when the carbs are dry. I broke the switch and
hadn't used the pump for a long time (at least 5 years) when I had trouble
starting it this spring. I poured gas in the carbs to get it running but the
mechanic pump wouldn't pick up fuel. I was ready to change that pump when I
decided to try the electric pump. I hot wired it and heard the familiar
rattling sound. The engine started up and the mechanical  pump started
working.

I'm sure not all electric pumps will allow the mechanical pump to pull gas
through them and there are probably some mechanical pumps that don't like
the electric pump forcing gas through them. I do know that the setup works
for me.

Spence Shepard
----- Original Message ----- 
From: "Smitty Smith" <vairologist at verizon.net>
To: <virtualvairs at corvair.org>
Sent: Friday, May 05, 2006 4:37 PM
Subject: <VV> Vapor Lock


> Smitty Says:  I know this will come as a total shock to many on the list,
but I am not an electric pump advocate.  Sometimes with reality staring us
in the eye we have to make compromises.  Mine would be an electric at the
tank with a push button to blow the gasious bubble out of the line.
>   Something for a lot of you to consider when talking on this subject.
Vapor lock does not occur in a Corvair when the engine is running.  Too much
nice cool air whistling down over the pump and lines for that.  Vapor lock
occurs after heat soak and when the engine is started the air doesn't have
time to cool the components before the bubble gets to the pump.  I consider
that to be truth, and therefore see no way that the recirculating return
line is going to prevent vapor lock as fuel is only flowing through it when
the pump is pumping.
>
>   ------------------------------------------------------------------------
--
> Been reading some of the vapor lock thread. I had my 140 Corsa vaporlock
on
> me yesterday evening. Car had sat 1/2 to 1 hour. Got down the road and it
> died. Cranked and cranked. Nothing. Pulled the air cleaner off, sure
enough,
> no fuel. Waited a bit for things to cool off. Fired up after a bit of
> cranking.
>
> I really don't want to do the electric pump, although I do see some
> benifits. For one, probably a bit more simpler than running a return line.
>
> If running a return line, would you tee in at the fuel pump on the 140 or
> get an inline filter with a return line on it? Where is a good place for
the
> filter, before or after the pump? What would be the best way to do this?
>
> Pros and cons of both ways?
>
> And this is with MTBE fuel.
>
> It's only happened once so far.
>
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