[Healeys] fuel pump

[Bob Haskell]

Bob,

The photo is of an OEM SU electronic pump.  Dave Dubois used an optical 
switch.  He removed the points from the toggle and soldered a brass vane 
on to it.  The attached image shows Dave's circuit board and the optical 
trigger epoxied to the pedestal.

He wrote in an article that you need some arcing to keep the points clean.

Bob Haskell
Austin-Healey 3000 roadster registrar

On 4/22/23 22:35, Bob Spidell wrote:
> 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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