This problem has been with us for a long time. The early pumps came with no
condenser across the points. This pump gave us many problerms. Someone came
up with a condenser. This was a great help to slow down the burning of the
points, but the problem was still with us. Then came the electronic age and
a diode was fitted. This just about stopped fuel pump problems. But we now
have another problem. The negative pump with diode is identified by a half
round bulge in the case has its cover sealed with black plastic tape, and the
postitive is sealed with red tape. When the supply on positive pumps ran
out, one supplier removed the diode from the negative pumps and called it a
positive ground. This takes the SU pump back 40 years to its problem days.
We have also found brand new pumps that have stopped due to incorrect
adjustment of the fuel pump diaphragm.. Refer to your factory service manual
for correct adjustment.