[Healeys] Fuel pumps (AGAIN!)

[Bob Spidell]

Once again, I am only relating my personal experiences with SU fuel 
pumps.  Some have experienced similar problems to mine, some have gone 
many years and many miles with no issues.  Look at the reviews for any 
common item on Amazon; there are often many who had good results with 
the item, and usually some who did not.  I'd like to find a common 
thread, but doubt that will happen.  I suspect those who drive their 
cars often--my mileage is mostly on one or two long road trips every 
year, and the cars may sit for a couple months at a time--will have 
better luck with points as, properly adjusted, the points mechanism is 
designed to 'wipe' the points with each activation.  Am told points 
pumps that have sat on the shelf for a long time before installation 
should have the points cleaned, as the (presumably) tungsten on the 
points will oxidize.

I got some points from a 'usual suspect' that came in a plain white 
box.  These points had a very shiny, silvery appearance--as opposed to 
tungsten which is a dull metallic color--and burned in just a few 
hundred miles.  Dave DuBois noted similar problems with some aftermarket 
points.  Presumably, genuine SU points are much better, but may not have 
been available at the time, or the vendor is cutting corners.  In 
theory, the 'solid state' pumps, triggered either by opto-electronic or 
Hall Effect switches, should go forever, perhaps needing an occasional 
diaphragm tension adjustment but, again, that hasn't been my experience.

WRT the vents, I agree.  I have had a tube on the vent on the pump body 
going to a safe, (usually) dry location (the boot) for years.  Some 
pumps have a rear vent (on the plastic electronics cap)  that is 
suitable for fitting a vent tube, some do not:

https://www.sufuelpump.com/collections/pumps/products/copy-of-azx-1308ep-1

Note the cap on the rear vent; it's been a couple years but last time I 
pulled the cap off the check valve ball came out--I wasn't expecting 
it--and I lost it.  I don't think you can fit a tube to these, but I'm 
not sure.  Others have a metal extension that appears to be designed to 
have a tube fitted.

I do appreciate all comments but saying, in effect "they don't do that" 
isn't adding any data points.  I don't claim to be an expert  mechanic, 
but I have maintained several cars for many years and did do a 
nuts-and-bolts, frame off restoration of a 100M, so I know which end of 
a wrench to grab.   Installing an SU fuel pump involves tightening nuts 
on a couple studs--I pre-fit them to my spares to facilitate a quick 
change-out--a couple banjos--which will let you know immediately if they 
aren't properly fitted and sealed--and one electrical lead.  I've had 
lots of experience, and successes, with that operation.

Bob


On 11/29/2018 2:14 AM, Kees Oudesluijs wrote:
>
> 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
>