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MG MGB Technical - Fuel Pump Issue

I have a postive ground SU fuel pump on my postive ground '67 B. It now has a strange habit of quitting every now and again. When it does this, the car will start running rough, then it will die. I will turn the key off, stop, turn the key back on, hop out of the car and touch a screwdriver to the outside of the pump and it will start ticking again. It may do it again in a couple of minutes, or it may be a few days or a week. So far I have checked all the ground wires in the boot and they seem to be in good order. I have also taken the pump out of the bracket, checked the wires there and reattached them all. However the problem continues. The fuel pump is rather new and has about 10K on it. It does not tick everytime I start the car, but I am guessing that it still has good pressure in those instances.

So the question for the group is: Is this a wire harness issue or a fuel pump issue?

Thanks!!!

Doug in ATL
Doug

Doug - Send me an e-mail and I'll send you a fuel delivery troubleshooting guide that will help you isolate your problem. The fact that the pulp will start right up when touching it with a screwdriver suggests that the points in the pump are dirty. You don't say how often you drive the car or if you have it laid up for the winter months, but prolonged disuse will allow a film to build up on the points and it can get bad enough that it will insulate the contacts form each other. Tapping the pump will vibrate the points enough to get the points to make contact and start pumping again. If this is the cause, running some 400 grit sand paper between the contacts will clean them up. See also my article on SU fuel pumps at: http://www.custompistols.com/cars/articles/dd_su_fuel_pumps_101.htm
Good luck - Dave
David DuBois

This thread was discussed on 11/04/2005

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