With regards to SU fuel pump polarity, the older pumps with a condenser
across the points WILL work for awhile if the polarity is reversed, but
the efficiency of the condenser at suppressing arcing across the points
will be reduced. The result? The pump points will fail after a few
thousand miles. Newer pumps with the diode suppressor instead of a
capacitor will NOT tolerate polarity reversal, the diode will fry if you
hook the pump up backwards, and the pump will not work.
You can tell a new diode equipped pump by the cylindrical bulge in the
plastic points cover, earlier pumps do not have this bulge. Also, new
pumps with the diode have the part number prefix AZX, whereas the
earlier pumps have the prefix AUD. As for why the positive ground pumps
are more expensive than the negative ground ones, it may be that there
are much fewer of the positive ground units produced. Instead of paying
a significant premium, you could buy a negative ground pump, open it up,
and switch the leads on the diode. This takes some fiddling since the
connectors on the lead ends are not identical. You could also write or
call Burlen Fuel Systems in the UK and order in the correct diode for
positive ground, they only cost about 5 bucks and can be shipped in the
mail.
As for the Dixon All British Car Show and Swap Meet, I will be there
RAIN or SHINE in the morning wearing a slightly tacky green ribbon as an
armband, denoting my participation on this List (and the MG BBS as well)
and my large blue and white SU carburetter umbrella. I will try to
locate Mark Bradakis, we should try to congregate at his vendor stall at
11 AM. See you there!
Cheers,
Paul Kile
(Not an SU employee, I just have a perverse liking for the technology!)
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