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Re: Classic fuel starvation 77B

To: "MG List" <mgs@autox.team.net>
Subject: Re: Classic fuel starvation 77B
From: Max Heim <mvheim@studiolimage.com>
Date: Sat, 24 Jun 2000 10:07:33 -0700
Check into it, 'cuz it can be more than annoying --- it can collapse your 
gas tank. No, no, not from the fuel pump's vacuum-producing power, but 
from fuel vapor condensing after a hot day. Say you're down to a few 
gallons of gas, and 10 gallons of fuel vapor, at the end of the day. As 
the temperature drops overnight, the vapor condenses, but... no air 
rushes in to take its place, because the vent is clogged. So a partial 
vacuum is created inside the tank, and normal atmospheric pressure 
squishes it flat. BTDT.

Bud Krueger had this to say:

>Still don't know why, but my gas cap vent - didn't.  Neither did the rest 
>of the
>system.  Yesterday morning I was in my commuting mode, running along 
>smoothly at
>60mph, when all of a sudden the engine sputtered and died as I pulled onto 
>the
>shoulder.  Sat there for a moment and pondered the world while listening 
>to the
>silence of 5:15 am.  After about a minute of contemplation, I turned the 
>key to
>listen for the fuel pump.  No sounds.  Turned the key farther - engine fired
>up.  Said "sonuvagun", or something like that that, and pulled back onto the
>highway.  About two miles up the road it happened again.  Pulled over on the
>shoulder - got out - went around to the back and loosened the gas cap. THUMP!
>You should have heard the sound of the tank sides expanding after the 
>inrush of
>air.  I'm very impressed with the ability of that SU pump to suck up some
>vacuum.  Left the cap at the first click and continued on my way.  Strikes me
>that this shouldn't happen in a '77B with the charcoal cannister still 
>plumbed
>into the vapor separator.  I'll check it out tomorrow.
>
>
>--
>Bud Krueger
>http://home.ici.net/~bkrueger/
>52TD x2
>77MGB
>
>
>


--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the red one with the silver bootlid.


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