[Healeys] Fuel pumps (AGAIN!)

Thu Nov 29 09:18:12 MST 2018

We install and sell probably about 50  to 75 SU fuel pump a year with almost 0 returns. The only time when we had an issue with the SU pumps is when they first came out with the Positive Ground pumps.

The reason for this is they went backwards in time about 50 years.

Originally the pumps only had a set of points and no condensor. Then they installed a condensor in the early 50s to solve the pitting points and sticking problems they were having. These pumps were used thru the early 80’s with very few issues other than failures due to age. Sometime in the late 80’s or early 90’s there was a demand for originallity for a Positive Ground pump at the time the had changed from a condensor to a diode in across the points. So the answer to a Positive Ground pump was to remove the diode. This returned the pump the original design and they started having pump failures in the Positive ground pumps.

Then somewhere in the late 90’s they started installing a non polarity concious diode in all the pumps. Thus solving the problem with pump failure due to the points. 

The one issue that we did find with the pumps in the late 90’s up until about 2005 was that the diaphgrams / points adjustments were incorrect. So we would always pull all of our pumps apart and re adjust the points to the factory settings as per SU.

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 
by visiting the site at.
www.britishsportscarhall.org

From: Al Fuller 
Sent: Thursday, November 29, 2018 5:55 AM
To: 'Kees Oudesluijs' ; healeys at autox.team.net 
Subject: Re: [Healeys] Fuel pumps (AGAIN!)

Kees:  I wonder whether you can confirm that you really intended below to refer to the experiences of those who have had issues as “some of you claim…”?  

If the SU-pumps would have been so unreliable as some of you claim, they would not have been used on such a large scale. Many millions of cars have had them in the 1930´s through to the 1990´s, from the humble Morris Minor to Rolls Royce.

Sounds like you doubt people’s “claims” to have been stuck on the side of the road, or under a teetering car with traffic passing by – covered in gasoline, or spending time in hotel rooms working on fuel pumps, etc.  As I said – just wondering whether you can confirm your intent…

Al Fuller

'65 BJ-8

'85 Rx-7

From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Kees Oudesluijs
Sent: Thursday, November 29, 2018 5:15 AM
To: healeys at autox.team.net
Subject: Re: [Healeys] Fuel pumps (AGAIN!)

It is not uncommon that a car´s service sheet also included the SU-pump (clean the points every service), e.g. Lotus Eclat/Elite. However I never did and I have had no problems. I used my car as a daily driver but it had to live outside all year. Nowadays the car is pampered in a heated garage and is mainly driven when the weather is suitable for open top driving except for long trips abroad.

The pressure delivered by an SU-pump depends on where the pump is situated. If it is fitted under the bonnet it should be a so called low-pressure or suction pump delivering 1,8psi (e.g. some Austin-Healey Sprite/Mg Midget). You can often recognise this pump by the 2BA screw (same size as the screws that hold the coil housing to the pump body) on the coil housing for the earth spade. If the pump is fitted near the petrol tank it should be a so-called pressure pump delivering 2,7psi (e.g. MGB) or 3,8psi (Austin-Healey 3000, Jaguar 6-cyl. cars MkII, E-type etc., Triumph Stag, Jensen-Healey a.o.). The high pressure pumps can be recognised by a smaller 4BA screw for the earth spade. The pressure is fixed and is controlled by the spring fitted under the diaphragm.  All pumps are identical as far as the coil housing, points system, diaphragm are concerned. The differences are in the pump body but this has no effect on the pressure, mainly on the variation of delivery pressure and flow rate. Some cars have the h.p. pump fitted on the chassis open to the elements (e.g. MGB, A-H), others have it protected in the boot (e.g. J-H).

There are three types of spring, the low pressure 1,8psi spring can be easily recognised as the wire is rather thin and it has more coils, the 2,7 an3,8psi springs have less coils and look identical to each other but the 3,8psi spring is slightly thicker and should have a (faint) dab of red paint.

If the SU-pumps would have been so unreliable as some of you claim, they would not have been used on such a large scale. Many millions of cars have had them in the 1930´s through to the 1990´s, from the humble Morris Minor to Rolls Royce.

Sure, the early ones did wear the points rather quickly because of arcing/spark erosion, but this was counteracted by proper maintenance which was usually every 1000 to 3000miles in the 30´s up to the 50´s. The wear was significantly reduced by using a simple capacitor (very like the capacitor in the points distributor), then a diode and lately Burlen fitting a transil. The pumps are dual polarity except when a diode is fitted. 

However spark erosion is not the main problem, that is electrolytic corrosion due to lack of use and dampish conditions under the cover because of improper ventilation like no tubes connected from the pump to a dry area of the car (boot) or no rubber band or friction tape on the joint of the cover and coil housing or damp storage.

I am not sure if the quality of the points you buy today is less than the old ones. I have never used them. I still have NOS points to replace worn points, but more often than once cleaning and repolishing the old points will do.

Kees Oudesluijs

  Not trying to reinvent the wheel, David, just get a fuel pump that lasts.  Others have had good service from points pumps like you, but I haven't.  I'm not doing anything unusual; if you get them installed and they don't leak and they run that's about all you can do--there's no trick or secret to installing them that I know of.  Mine just keep failing, with between a few hundred and up to 15K miles of service (this over about 140,000 miles I've put on my BJ8).   I will say I have driven through some serious downpours, so water entry into the switching compartment could be a problem, but some of the failures didn't get drowned.

  The points can be problematic, else SU wouldn't have gone from:

  1) no arc suppression

  2) capacitor arc suppression

  3) diode arc suppression

  That is to say, SU wouldn't have gone to the expense and labor of installing capacitors and diodes if there wasn't some issue with reliability or longevity.  I tried all three, with results as noted.  I've installed the out-of-the-box, rebuilt and adjusted them myself, installed SS switching mechanism, used capacitors, diodes, TVSes, transistors and installed SU electronic out-of-the box with predictable results.  I do recall your dad either writing or saying that they used to take the pumps out and service them--cleaning the points and adjusting the mechanism I presume--at 15K mile service when he worked at BMC (or was it BL, don't recall), so they aren't typically bulletproof forever.   

  Maybe I pissed the SU gods off somehow; though both my sets of SU carbs have been all but bulletproof, and the basic points-type in my BN2 has worked for a few hundred miles.

  Bob

  On 11/28/2018 9:50 AM, healeydoc at gmail.com wrote:

    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 
    by visiting the site at.
    www.britishsportscarhall.org

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