I rebuild/overhaul SU (mostly AUF300/AZX1300 series) fuel pumps using
the standard points and adding a transil across the points to limit the
voltage across the points thus preventing arcing. It also makes the pump
dual polarity. Keeping the points means that it is possible to attend to
the fuel pump at the roadside if need be. Electronically converted
pumps, be it with an optical or magnetic system, are supposed to be
reliable but if they go wrong, and they sometimes do,? that?s it.
It is easy to rebuild these pumps. Very often it is only necessary to
clean and polish the points and properly set the point gaps, spring
blade front to bridge 0,9mm and tumbler to cast iron body 2,3mm, some
say 1,8mm but that is a very early setting. Replacement is easy but
dismantling the pump is needed.
If the pump has not been in use for a long time the internals may have
corroded. The valves may than need replacement. Dismantle the pump,
clean and rebuild. The old triple layer diaphragm is nearly always in
good serviceable condition and preferable to a new single layer one. It
may feel a bit stif, but this is usually caused by the layers being
stuck together. Just pry the layers apart very carefully, especially the
very thin kevlar membrane and apply just a smear of talcum powder
between the layers.
There are plenty of sites you can Google for the rebuilding process.
Kees Oudesluijs
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