[DeTomaso] Fuel Pump Plumbing

Sun Jul 20 11:11:37 EDT 2008

By the way, I went through the same issue a couple of years ago.  I tried
the electric pump pushing into a mechanical pump.  It didn't help.  My
problem?  I had a small filter between the bottom of the tank and the pump.
It was completely plugged with tank rust.

I don't know of a site that describes how to replace the mechanical pump,
but here's a quick how-to:

1.  Remove the gas lines from the pump.  There should be 2 lines at the
bottom of the mech pump.  When you remove the lines, a little bit of gas
should come out, but not much - maybe enough for a shot glass.  By the way,
if your fuel line is plumbed to the bottom of the tank (instead of the stock
location at the top of the tank), it's a different story.  You'll have Mount
St. Helens only with gas instead of ash.  Make sure you have enough gas cans
standing by to catch all the gas in your tank.  Been there.

2.  There are 2 bolts holding the pump to the block.  Actually, one is a
bolt, the other is a nut on a stud.  This part is tedious.  You can only do
about 1/4 turn at a time.  I've always done this from inside the car with
the bulkhead cover removed.  If you can reach it better from under the car,
go for it.

3.  Once the 2 bolts are removed, the pump comes right out.

4.  The new pump goes back the same way the old pump came out, but there are
3 tricks I've used:  (mutually exclusive)

    a. Remove the water pump and timing chain cover.  I wouldn't do that
just to replace the fuel pump, but if you were changing the water pump,
timing chain, or camshaft anyway, it's a lot easier to install the fuel pump
with the timing cover removed.

    b. Scream. Grunt. Cuss.  In that order.  As a last resort, cry.

    c. Turn the engine over to TDC on #1 (timing marks at 0deg on balancer).
It should be 180deg out from firing on #1.  How can you tell?  The rotor
will be pointing away from the #1 plug wire.  At this position, the fuel
pump eccentric is pointing up.  Why is that important?  It's a lot easier to
get the new pump installed.  The arm doesn't have as much pressure on it.

5.  Reinstall the fuel lines.

The best fuel filter I've seen was at a dirt-track oriented speed shop.
They're about 5" long.  They consist of an aluminum tube with A/N fittings
on each side and a large metal screen on the inside.  They're about $35-$50.
They require A/N fittings.  You don't have to do a full A/N conversion.  You
can hook braided A/N fuel line to standard hose barbs.  You could do A/N on
the filter, and A/N from the pump to the filter, and then use a regular hose
barb at the carburetor.

I'm sure there are great filters that don't use A/N fittings.  The larger
the better.

Oh yeah, I don't know how much H/P the 80gph can handle, but it's plenty for
everyone unless you're running a track-only car.

Will.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of clay willmott
Sent: Sunday, July 20, 2008 8:08 AM
To: Will Kooiman
Cc: List Pantera
Subject: Re: [DeTomaso] Fuel Pump Plumbing

Thanks Will.
I looked at the Holley 80 gph mechanical pump.  I had no idea it was mounted
to interact with the eccentric camshaft lobe.
Any advice or internet sites that go over how to install one on a Pantera?
I have never had to work on a timing chain, camshaft, or mechanical pump
before.
How many HP does 80 gph support?  Where did you mount your filter and what
type did you use with your mechanical pump?

Clay

> From: wkooiman at earthlink.net
> To: claywillmott at hotmail.com; detomaso at realbig.com
> Subject: RE: [DeTomaso] Fuel Pump Plumbing
> Date: Sat, 19 Jul 2008 20:37:37 -0500
> 
> 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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