This weekend's project was to figure out why the MGB's fuel pump
was intermittently cutting out. We remove the pump from the car and
wonder _why_ they had to put two breather hoses on it.
Some testing on the bench reveals that the points are not
totally happy. Adjusting them by rotating the diaphagm gets that
working well. However, the diaphragm itself is stiff and really
doesn't look very good. We reassembled the pump anyway, and discover
it doesn't work at all now. it goes ticka-ticka, but there is no
pressure to be had.
We can either rebuild the pump, or replace it. After calling
around and discussing options, we decided to put in a Facet pump.
Incidently, these are also sold under the Purolator label. Be sure to
get the low pressure type. You might be able to use the higher pressure
model with the Globe float valves. I have them, but was not interested
in experimenting.
A Fram GA22 gas filter screws directly into the pump inlet.
This makes for a clean installation with only two hoses and attendant clamps.
Well, the new pump works much better except that it is a good
deal noisier than the SU. It doesn't seem to put out nearly the radio
interference that the SU does though. When bench testing the SU, we
discovered (the hard way) that it puts out 60-80 volt NEGATIVE pulses
from the coil when the contacts break. The diode someone mentioned
probably does a good job of supressing them.
Another interesting effect of the new pump is more power. It
seems that the engine was getting starved for fuel at high RPM. This
set on very slowly so it kind of snuck up on me.
Incidently, it was cheaper to replace the SU with the Facet
than it was to rebuild the SU.
Next installment. . . A guest appearance by Dr. Christian
Barnard to discuss carburetter transplants.
Happy Motoring,
Dave Ambrose
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