[DeTomaso] Fuel Pump Plumbing

[Will Kooiman]

It's probably not the best idea to use a Holley red to suck the gas out the
top of the tank.  Most electric pumps don't like to suck.

It should work fine if it's plumbed to the bottom of the tank, though.

You shouldn't need to run 2 pumps.  That's the wrong solution.

Here are the things I'd check:

1.  Vacuum in your gas tank.  When it dies, open the gas cap.  If it sucks
air, you have a venting problem.
2.  Plugged fuel filter.  Even if it's brand new, it could be plugged -
especially if you just cleaned the tank.  Remove the filter, hold it upside
down - so that the direction of flow is pointing down.  Does gas come out?
Turn it the other way.  Does gas come out?  If gravity can't push gas
through the filter, a pump isn't going to push it either.
3.  Fuel filter on the suction side.  It's a lot easier to push fuel than it
is to suck it.  I always put one filter on the pressure side.
4.  It could be crap in the fuel passages in your carburetor - right before
the needle/seat.
5.  Vapor lock gets blamed a lot, but it's probably the least likely.  It's
not like you have fuel lines running across the headers or anything.

By the way, I prefer mechanical pumps.  They worked fine for many years.  An
electric pump is one more thing to fail.  Unfortunately, there aren't a lot
of good pumps for 351C's.  I like the Holley Chrome pump.  It has a thick
diaphragm.  I've used a cheap Autozone pump.  The diaphragm looked like a
bicycle inner tube.  I want to try the pumps from Rob Mcquarie.

Gotta go,
Later,

Will. 

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of clay willmott
Sent: Saturday, July 19, 2008 3:25 PM
To: List Pantera
Subject: [DeTomaso] Fuel Pump Plumbing





Does anyone have an electric fuel pump that both pushes and pulls on their
Pantera?
Mine
is set up with a Holley Red from a new fuel sender.  It came this way
and I am thinking of trying a puller plus pusher style pump prior to
changing to the Holley 80 gph mechanical pump.  Although, if I ran from the
tank drain plug to the fuel pump the extra gravity would eliminate the
pulling need I think.
After changing all
my lines to SS, new fuel filters and pump, looking in gas tank twice
(no debris)  I had another engine kill after driving for about 20
minutes. The car restarted and ran well after 5-8 minutes of cooling
off.  I was told vapor lock would not regress so quickly and that a
Holley Red may not be the best pump to pull from the top of a tank and
may intermittently not be able to keep fuel delivery up to par.  When I
tried to restart it to get it out of the road it would run 1-2 seconds,
advancing all of 1-2 feet then die like an engine that is out of gas. 
I had a 1/2 tank, engine temp and oil pressure were fine.

I put
my inline fuel pressure gauge back on and will leave it there and if
this recurs check the fuel pressure during the episode.   
Any other suggestions?
I
was told removing the air filter right when this happens and peering
down the carb may answer the question but I am not sure why unless it
diagnosis vapor lock.  Or can you normally see the fuel in the float
bowl and if it is not there that would indicate vapor lock or a pump
not receiving adequate fuel?

Any help appreciated.


Clay
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