[Mg-t] SU Low Pressure Fuel Pump

[Stuart Keen]

I was inspecting/adjust the two SU fuel pumps on my 1951 MG TD MKII. Both
function, but they are not built the same and I was wondering if this could
be a design change or a problem later on.

One pump does not have any armature guide rollers. The workshop manual calls
for 11 single rollers but in lieu of the single ones, my other pump has 5
double rollers, sort of looking like 3O-O2. Must be a design change. My
question, are rollers necessary/important? The six bolts that marry the
whole assembly together should align the diaphragm anyway . . . Or am I just
assuming too much?

I also noticed that that the diaphragm of the same pump did not have a
plastic sheet barrier between the rubber diaphragm and the fuel like the
other pump. Is this plastic necessary? What9s its purpose - to keep fuel
away from possible leaks to the electrical? Without the plastic, the rubber
diaphragm would be exposed to fuel. Perhaps the rubber would deteriorate?
However, the diaphragm looks brand new so perhaps it comes now without the
plastic. Anyone have any knowledge about this?

Is it possible that the lack of guide rollers and plastic barrier is a later
design change?

Stu Keen
1951 MG TD MKII