Mechanical fuel pumps pull the gasoline from the tank to the engine,
effectively lowering the pressure of the fuel in the line. Just as a
pressure cooker - or lower altitude - raises the boiling point of a
liquid, lower pressure - or higher altitude - lowers the boiling
point.
So, you're cruising along at 50-60 mph, with the windows down, the air
blowing through your hair (I can dream, can't I? <G>> and it's purring
like a kitten. Then, you pass the sign with those two dreaded
words... "Road Construction." You're down to a crawl, the temp gauge
rises a bit, and, all of a sudden, that beautiful purr ceases. Yep,
silence, except for the popping of metal expanding unevenly. The fuel
in the line between the tank and the pump - where it runs (too) near
the transmission or engine - has boiled, and, guess what? it's a fuel
pump, not an air pump, so, no more "go." If that wasn't enough, when
the engine stops, so does the pump - kind of a Catch-22.
That's one of the reasons they started using electric pumps, mounted
in or near the tank. The pump pushes the gas, resulting in higher
pressure in the line, with a correspondingly higher boiling point.
But, even if it does vaporize a little bit, the pump just keeps
jamming liquefied gasoline up the line, anyway.
That's pretty much the way my Dad explained it to me, years ago -
although he never installed an after market electric fuel pump...
--
Lewis - K7LVO - Medford - Valley of the Rogue - OR
The Forty - 1940 Chevy Pickup - One Owner
http://www.teleport.com/~losborn/1940.html
Thursday, July 27, 2000, 4:04:13 PM, Deve wrote:
> I am sure its just me, but I regard vapor lock along the same lines as Deer
> Whistles or Snipe Hunting. When there is no gas, its a plugged or restricted
> fuel line, when its no spark but only dies when hot, its usually a coil. Of
> course it could be other things related, but vapor lock on an old truck is
> rare to non existent. These things ran in any weather, any time. There is no
> tougher or more reliable thing on the planet than an old 6 cylinder chevy
> truck. Too many years of experience with these things with no vapor lock to
> suspect it now. Of course a few more years and/or dealing with the public
> too often and I could vapor lock, but thats another story!
> Deve Krehbiel
> Hesston, Kansas
> 1950 3100 * 1949 3600
> www.speedprint.com/Deves50/index.html
> ----- Original Message -----
> From: "Joseph Szwed" <szwedj@viagate.com>
> To: "Oletrucks List" <oletrucks@autox.team.net>
> Sent: Wednesday, July 26, 2000 4:15 PM
> Subject: Re: [oletrucks] vapor lock remedies
>> The vapor lock problem seems to come up quite a bit and usually the
> replies
>> are pretty standard.
>> On an old tractor list that I am on, it seems quite a few guys have
> recently
>> had problems with this also.
>> Some guys thought it had to do with the additives and oxygenators being
>> added to the gas, and that it lowered the boiling point.
>> Anyway some guys claimed by adding a little diesel fuel to their gas the
>> problem went away.
>> Just wondering if anyone else heard of this or tried it.
>>
>> Joe Szwed
>> Stockton, NJ
>> 50 Chevy / 51 GMC
>>
>> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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