I use dual fuel pumps in my Spitfire because the ATL fuel cell has dual
pickups. They both feed to a common tee, so I suppose one could feed through
the tee to the other -- but since I always have both operating at the same
time I've never noticed any kind of backflow problem. I have no checkvalves
on them.
One of the ATL duckfoot pickups goes to each back corner of the cell, thus
no matter in a left or right turn, at least one of the pickups is drawing
fuel no matter how low (assuming not empty!). That's why I run both
simultaneously -- it's not a case of waiting for one to quit, then turning
on the other.
My pumps are both Holley reds. I tried the Facet and one other brand I
forget now -- they both lasted less than a month before thei died. Then I
bought a Holley blue, but fortunately someone who knew better saw me with it
and told me it was too much pump (15 psi pressure?) for my car. The red
delivers about 7.5 psi -- and they cost the same so it was a straight swap.
Then I got the cell and the second Holley. They've run fine for 8-9 years
now and I'm very happy with them. The regulator up front holds the flow to
about 2.5.
The only "problem" I've ever had is learning the vanes may rust inside the
pump, especially after sitting idle all winter. It doesn't take much rust
(water in the fuel) to make the vane stick. It is a simple matter to unbolt
the bottom of the pump, clean things out, scrub the rust off the vanes
(emery paper or fine sandpaper does it) and put it back together. Just good
preventive maintenance. Cannot really expect something with moving parts to
run forever without maintenance.
--Rocky
----- Original Message -----
From: "Henry Frye" <henry@henryfrye.com>
To: <fot@autox.team.net>
Sent: Saturday, August 09, 2003 8:59 AM
Subject: Fuel Pumps
> I have been playing with the idea of running dual fuel pumps for a while
> now. If I drop in a second pump, I assume I need a pair of check valves so
> I don't backfeed the cell through a non-operating pump. True? What check
> valves should I use?
>
> I have been fighting fuel problems ever since I changed out a little Facet
> cube pump and an el-cheapo fuel pressure regulator for a Holley Blue Top
> pump and a Holley regulator. My fuel pressure gauge would show an
> intermittent fluttering accompanied by a distinct buzzing coming from the
> regulator. I swapped the regulator, I tried both the 1 to 4 PSI and the
4.5
> to 9 PSI regulator that comes packaged with the fuel pump. Both did this
> from time to time with the engine running or not. At Mosport I had things
> running pretty well (with notable exceptions!) but running the Triumph
> feature I found some times the car would take full throttle happily, and
> some times it seemed to bog down at anything more than 4/5th throttle.
>
> So I decided to replace the fuel delivery system from the pump to the
> carbs. I ran new 3/8th's inch hard line from the pump to the new
regulator.
> While I had the pump in hand, I decided to drop the bottom off and take a
look.
>
> The pump is of the basic rotor and vane variety, the rotor sits off-center
> in the round pump bore, and 4 little vanes slide in slots in the rotor. As
> the rotor turns each vane slides in and out of it's slot, remaining in
> constant contact with the bore. Centrifugal force at play here.
>
> I found the pump cavity as clean as I could have hoped for, the debris
> screen was perfectly clean. I spun the rotor by hand, and I found my
> smoking gun. One of the vanes was stuck in it's slot. It easily became
> unstuck with a tiny amount of encouragement, but no doubt the vane was not
> doing what it was supposed to. Holley sells a rotor and vane replacement
> kit, which I installed, but I have lost all confidence in the design of
the
> pump. I see no reason for this failure to have happened. The rotor and
> vanes I removed from the pump look fine, and the vanes slide freely in the
> slots. Perhaps something in the race fuel???
>
> Any recommendations on fuel pumps OTHER than Holley?
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