RE: [DML] Overheating Fuel Tank.

["Scott Mueller" <scott.a.mueller@xxxx>]

Robert,
When the gasoline heats up, it is more prone to vaporize in the pump suction
and cause cavitation. Cavitation sounds like gravel going through your
pump. The three major sources of heat are the coolant piping along side the
tank, hot air from the radiators and heat form the engine via the fuel
return line.



Scott Mueller
002981
scott.a.mueller (at) att.net

-----Original Message-----
From: therealdmcvegas [mailto:DMCVegas@xxxx]
Sent: Thursday, May 16, 2002 5:28 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] Overheating Fuel Tank.


So far, my car has been ok thru the early summer heat. But
Tuesday I had to make a trip across town forr my job. And I had
the car parked outside the whole day. Long story short, my fuel
pump became quite noisy. So much so to the point where I coulf
feel the vibration from the fuel line thru the center console!
Durring this time, I also noticed that my voltage took a severe
drop @ idle. With the A/C on, and the fan on speed 2, the needle
was down to the 2nd mark on the voltmeter! Usually I can only
hit that mark with the fan on 4, rear defroster, and all clearance
lamps & high beams on! So, my guess is not that the fuel hose
is collapsing ( there is a spring installed), but that the excess
heat in the tank is causing the internals of the pump to expand,
and thus grind making the sound. The kicker though, was this.
When I parked the car for 20 minutes, and got back in, the sound
was worse! After driving about 4-5 miles, it did quiet back down a
bit. But did not improve from where it was before. With the
exception of after I parked the car, and until the fuel cooled a bit,
the accelleration on my car was fine.

Now, from all this, I have determined the following:
1. A noisy fuel pump isn't always due to a collapsing fuel pick-up
hose.
2. Air flow from the front radiator is NOT heating the fuel. When I
stopped the air flow, the noise became worse. It wasn't until I
restored air flow that there was a sign of cooling.

So, I've determined that the heat MUST be comming from the
coolant pipes that run along the sides of the fuel cell (I do
believe that Walt mentioned this one before). So, now I have the
following questions. I've seen ads that giving a ceramic coating
to exhaut pipes helps to keep the heat inside of them, and
reduces the heat in the engine compartment. Does this really
work? If so, can I expect the same results for the two sections of
pipe next to the tank? This is the only "safe" solution that comes
to mind. I've no idea what kind of a reaction household insulation
would have with high water temps and/or chemicals found in
that region of the car.

Venting the tank to air flow is another entire possibility, but I have
concerns about aerodynamics and compromising the integrity of
the plate protecting the tank on the bottom.

Ideas?

-Robert
vin 6585 "X"