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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