[Healeys] S U fuel pump

Kees Oudesluijs coudesluijs at chello.nl
Tue Oct 20 09:52:09 MDT 2020

The problem with these pumps is mainly lack of use of the car. This will 
cause the points to corrode.

Although I do not use my car very much these days I have not encountered 
any problems in the past 12 years / ±40.000mls after I rebuild an 
original AUF301 SU fuel pump. However the car is kept in a very dry and 
heated garage.

Quick wear of new points may also be caused by not cleaning/polishing 
them before installing. However there could also be a quality issue with 
new points. That is why I prefer using old points that may be a bit worn 
but are still serviceable enough to polish.

Dave Dubois designed an optical switch to replace the points. The system 
is still being fitted by Pel de Haas in the Netherlands who cooperated 
with Dave.

Kees Oudesluijs

Op 20-10-2020 om 17:18 schreef Bob Spidell:
> The late Dave DuBois, who designed the transistor-switch fix, quit 
> doing the conversions when he found the reduced voltage cross the 
> points allowed them to oxidize. I tried the transil fix, but didn't 
> get much more longevity than a stock points setup with a diode; I do 
> know some have had better luck with them.
> I have a points/diode pump in my BN2 that works well, but I only have 
> a few hundred miles in the car. I've lost track of what I've got in my 
> BJ8.
> Bob
> On 10/19/2020 11:31 PM, Kees Oudesluijs via Healeys wrote:
>> When rebuilding SU electrical fuel pumps I ad a transil (e.g.. 1.5 
>> KE18CA) over the points, parallel or in stead of the capacitor if 
>> fitted. This reduces the max voltage across the points to 18V instead 
>> of several hundreds when the contact is broken and the points spark.
>> It is also important to clean and polish the points using flower 
>> paper (2-3000 grid), also when new!!
>> A transil is more or less a bi-directional Zener diode. They cost 
>> next to nothing. I buy them in bulk and pay about $0,15 but when 
>> buying only one expect  to pay between $1 and $5. Ebay is an 
>> excellent way to source transils (mainly from China).
>> A transistor circuit similar to those used in early transistorised 
>> ignition systems does a similar job by limiting the current through 
>> the points.
>> Kees Oudesluijs
>> Op 20-10-2020 om 07:50 schreef Ray Juncal via Healeys:
>>> I'm rebuilding a couple of early S. U. fuel pumps for my 100. In 
>>> checking my reference files I came across an article from the MG 
>>> club about adding a transistor circuit to reduce the amps across the 
>>> points. That would keep the points from burning and extend the life 
>>> of the points. Has anyone on the list tried this? The author of the 
>>> article claims he has 20,000 miles on the conversion and new looking 
>>> contact points. Thoughts, comments, suggestions.....
>>> Regards
>>> Ray
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