[Healeys] Fuel pumps (AGAIN!)

Wed Nov 28 21:26:53 MST 2018

This discussion about fuel pumps has revived something from the old grey
matter ...
To those mentioning repeated failures one problem that will cause premature
failure is restrictions in the supply to the pump.
The way these pumps work is that the spring in the pump provides the
pressure. As the pressure on the output side of the pump decreases the
diaphragm moves down to a point where the points close, that energizes the
coil to pull the armature up against the spring pressure to the point where
the points "flip" and open to stop the current flow through the coil.
HOWEVER if there is a restriction in the fuel line feeding the pump the low
pressure at the pump inlet can create a partial vacuum which will prevent
the armature from rising fully and thus the points from "flipping" .
When this happens the coil remains energized and "cooks" in a short time
thus ruining the pump.
I discovered this while trying to resolve a delivery problem in a car that
had had the tank "sloshed". The sloshing compound had coated the gauze
filter  inside the tank severly restricting the flow.
The test was to put an analogue ammeter on the pump electrical supply which
showed the prolonged current flow to the pump.

M

On Wed, Nov 28, 2018, 9:45 PM Kees Oudesluijs <coudesluijs at chello.nl wrote:

> Quite so. The only thing I can come up with is the car is hardly being
> used and being stored in dampish non ventilated conditions, thus corroding
> the points. As I said before I have had SU fuel pumps in from more than 50
> years old which were absolutely perfect except for the points corroded
> because the car was not used enough or worn because of not being adjusted
> properly.
>
> If used regularly and kept dry internally they last forever.
>
> Another thing: If you have had to tap the pump to get it going,
> replace/polish and adjust the points ASAP. Do not wait until you have to
> repeat the tapping.
>
> When fitting a new SU-pump you best remove the cap to inspect and if
> needed clean the points first with very fine polishing paper, I use at
> least 1000. It is even not uncommon that brand new pumps that have been on
> the shelf for a while, either at home, in the garage or at the suppliers do
> not work because the points are dirty/corroded and have to be attended to
> first. I have bought many pumps that were sold as "defective, for spares or
> repair"  for a song, that did not work and appeared to be in fact NOS.
> Cleaning and polishing the points was all that was needed for these. If you
> have a new/rebuild spare pump in store , remove the cap and insert a bit of
> acid free paper in between the points, this will stop electrolytic
> corrosion.
>
> In the late 70´s I was collecting  quite a lot of Jensen parts and got
> presented a new pump by Jensen Parts & Service that was said to be
> defective but only needed some small attention. My old pump kept working
> (more than 160000mls) so the new pump was never needed. About 5 or 6 years
> ago I came across that pump and decided to have a look inside. It was of
> course mint but there were real cauliflowers around the points. Just
> polished them, fitted a transil (as I do with all my rebuilds) and is now
> in my present car.
>
>
> Kees Oudesluijs
>
>
>
> Op 28-11-2018 om 18:50 schreef healeydoc at gmail.com:
>
> I do not understand the problem with the SU pump that everyone feels that
> they have to re invent the wheel. I have using the standard SU pump with
> points in my Healey for almost 75000 miles and never had a failure.
>
> We also have been installing the standard SU points pump here at the shop
> on every car we do for over 40 years
> Everything from Healey’s, MG’s and Jaguar’s and had very few failures.
>
>
>
> David Nock
> healeydoc at sbcglobal.net
> 209 948 8767
> www.britishcarspecialists.com
>
> Help us have our Founder Norman Nock inducteed into the
> British Sportscar Hall of Fame, You can vote for your favorites
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>
> *From:* Tom <ah3000me at gmail.com>
> *Sent:* Wednesday, November 28, 2018 6:00 AM
> *To:* healeys at autox.team.net
> *Subject:* Re: [Healeys] Fuel pumps (AGAIN!)
>
> I found the voltage regulator was misadjusted when i got my car.  At 17V,
> a new pump quit working in less than a year.  At 14V, the replacement is 10
> years old and happily ticking away.
>
> Tom
>
> On Tue, Nov 27, 2018, 9:16 PM Frank Magnusson <fmags at cox.net wrote:
>
>> Hi Bob,
>>
>>
>>
>> I’m also not sure why you’re having problems with pumps.  Maybe something
>> common between all of them; the vent, the ground, the venting of the fuel
>> system, etc.
>>
>>
>>
>> I replaced my original pump in the late 80’s with a stock SU pump with
>> points and it’s been on the car ever since; no problems except last year
>> when it didn’t want to start, but a rap with a rubber mallet and it’s been
>> working ever since.
>>
>>
>>
>> Try Healey Surgeons for a replacement pump.  Their parts are 100% correct
>> and I’ve never had a problem with anything from them in almost 30 years.
>>
>>
>>
>> Best of luck,
>>
>> Frank
>>
>> ’65 BJ8
>>
>>
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