Sounds like a valve inside the pump has failed. The SU is really not
difficult to get going. Blow and suck through the inlet and outlet to
check if the? valves are OK. This is usually the case. If in order do
not dismantle the pump body. /*Make sure there is no petrol inside as
this can be dangerous when breathing in!!!!!*/
Remove top cover. Mark the relative position of the pump and coil
housing. Remove the 6 screws holding pump body and coil housing
together,? carefully prise the 3 layer diaphragm loose, taking care not
to damage the thin keflar layer, it may need a few light taps on the
coil housing. Prise the layers apart and use some talcum powder very
sparingly in between the layers. Remove the diaphragm assembly by
turning it anti clock wise. Remove the bridge on which the contact
points are fitted, remove the contact points (be carefull not to damage
the bridge when extracting the case hardened pin) and inspect if they
are serviceable. Note the sequence of the various rings. There is also a
small lead ring fitted on the brass terminal screw which is a bit
awkward to remove. You can replace this later with a ring bend from
solder wire. Note down the way the wires/diode or capacitor are fitted.
I always replace the diode or capacitor with a transil (limit 18V) to
prevent spark erosion. This will also make the pump both positive and
negative earth.
Use some 400 grade sandpaper to remove the dirt and pits and polish the
points with 2000 grade flowerpaper. Also use the flowerpaper to clean
the pin. If necessary replace the points and polish them with
flowerpaper before fitting.
Fit the points, brass screw and bridge but take care not to overtighten
the screws as you may crack the bridge, making sure the lower set of
points can tumble. Fit the diaphragm, spring by pushing it up in the
threaded hole in the lower points assembly, this can be a bit fiddly,
and turn the diaphragm clockwise untill the contact point just do not
tumble any more when firmly pressing up the diaphragm, than screw it
back a bit until? the screw holes line up and than another 4 screw holes.
Fit pump and coil housing together using the gasket between the keflar
layer of the diaphragm and pump housing (you can make up one yourself if
the old one is damaged).
Now adjust the points by bending the tabs on the lower points assembly:
0,9mm between the upper points blade and the top of the bridge at the
front and 2,3mm between the lower tab and the coil housing.
Fit the cap, seal the cap using some tape and you are done.
If you have an older pump using Bakelite for the bridge and cap you can
repair them using Araldite when there are cracks or breaks.
There are some instructive videos on youtube and when Googling you will
find instructions for the repair, adjusting of the SU pumps. In older
publications you will probably find the 2,3mm gap above should be 1,8mm,
just ignore.
There are some variations in older contact points which means that the
adjustment is a bit different, but it is unlikely that these points are
fitted. Again the adjustment specs can be found using Google.
In very rare cases the coil has been damaged. This can be replaced. The
coils of most SU-pumps are identical and can be swapped.
Kees Oudesluijs
Op 28-5-2018 om 03:18 schreef Stephen Hutchings:
> I have a Hardi fuel pump, which is very similar to the S.U. in design-
> I put it on because when I switched to negative ground I had one on
> the shelf, and it was ready to go, rather than converting the S.U.
> After a few thousand miles, it's suddenly started to keep on clicking,
> rather than the occasional click once it's filled up. I can't find a
> leak anywhere, and the tank is full...so I don't know how it could be
> sucking air.
> Anyone know what to look for next?
>
> PS, I got my old S.U. pump and changed the polarity of the diode, but
> after fiddling with the points the way I used to, I've had no luck
> getting it going...it had been sitting a while.
>
> Stephen, BJ8
>
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