lucas fuel pump has electrical fault and doesnt bleed air?

car plays up intimitantly, runs then at low revs the car will rev right up by itself and then cut out and the glowplug light comes on, you go to start it up agen and revs right up and so on so on.... eventually gets going again, had a mechanic check the fuel system found no air getting into the lines except for some air around the pump is this an indication that the pump is failing? and what would be the best step to take from here?