[Healeys] fuel pump

[Bob Spidell]

Hoo boy ... SU pumps have been a personal bugaboo for decades. I have tried:

- points with capacitors (SU and home-rolled)

- points with diodes (SU and home-rolled)

- points with TVS diodes

- points switching power transistors

- SS with SU conversion kits

- SS from SU

Earlier pumps had no arc-suppression, then SU added capacitors (similar 
function to condensors with ignition points), then diodes in a 
'flywheel' circuit, to shunt the large voltage/current 'backflow' from 
the pump body/solenoid. The SU SS pumps use a Hall Effect sensor to 
switch a transistor (similar to what Pertronix uses). The late Dave 
DuBois--who all but dedicated his retirement to designing a bulletproof 
pump--used an optical sensor for switching (I believe he also designed 
the points/transistor system which was unsuitable because it DIDN'T 
allow sufficient current across the points to clean them).

It's a crapshoot; some owners report years of reliable function from 
points-based systems; some SS units don't last long at all. Dave DuBois 
was a meticulous rebuilder--he would run pumps on a test rig for 24 
hours before shipping--but I never got infinite reliability with them. 
Like Richard said, you can keep a points pump going with a whack from a 
hammer, or pull the pump off, file the points and readjust the preload 
on the solenoid to get you home (I once rebuilt one in a hotel room). 
I've got 2 or 3 pumps for my BN2--I forget which one's in there--but 
always carry a spare. Towards the end of my extended trips--up to 5K 
miles--I carried two spares in my BJ8 and have enough parts and partials 
to assemble a couple.

It's been a few years, but the last time I sourced points sets they were 
crap; they appeared to be made with a shiny metal like silver, and they 
should be made out of tungsten, which is a dull grey color. The 'silver' 
ones would start eroding within just a few miles. Anyone know if decent 
points are available (last I heard there's a similar issue with ignition 
points)? One issue with points is their arcing, if not sufficiently 
suppressed, generates ozone which can quickly corrode internals, so make 
sure the one-way vent valve on the control end is functioning properly. 
FWIW, I haven't seen a failure that I can definitively attribute to 
contemporary fuel blends.

It's some consolation, I suppose, that even modern fuel pumps are known 
to fail; but with some of them you have to pull the tank out to get to 
them. And don't get me started on engine-driven pumps with 6V ignition 
systems (it's a toss-up if the engine starts before the battery dies).

Attached photo is either one of Dave's rebuilt units or an OEM SU; I 
still don't have a clue why that happened (I think Dave eventually went 
to a Hall Effect setup, too; my memory is blurry).

On 4/22/2023 5:47 PM, Jean Caron wrote:
> Why not rebuild the fuel pump?
>
> Jean
>
>
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