The MGC is fitted with an SU electric fuel pump, the same type as used on the contemporary MGB (1967 to 1969 specification). The pump is mounted behind the heelboard on the right-hand side of the car, inboard of the forward rear spring hanger, and delivers fuel at low pressure to the twin SU HS6 carburettors. The MGC was fitted with the AUF 303 specification pump. The C-series engine block casting retains the mechanical fuel pump mounting aperture from its Austin-Healey ancestry, but this was never used on the MGC, it is sealed by a blanking plate with gasket and two screws with spring washers.
Pump Repair and Replacement
The SU electric pump is a rebuildable unit. A repair kit provides the diaphragm, valves, and seals needed to restore the pump to full function, symptoms of a failing pump include difficulty starting after the car has stood (fuel drains back to the tank through a leaking valve), fuel starvation under load (a weakened diaphragm cannot maintain delivery volume), and audible buzzing without fuel delivery (points failure or diaphragm deterioration). A new or reconditioned pump is the alternative where the pump body is worn beyond the scope of a repair kit.
Banjo Unions and Connections
Two banjo unions connect the fuel delivery pipe to the pump inlet and the pump outlet to the main feed pipe running forward to the carburettors. Each banjo union uses a banjo bolt and two fibre washers, one on each side of the banjo eye, to create a fuel-tight seal. The fibre washers must be replaced whenever a banjo union is disturbed, as they compress on first tightening and will not reseal reliably if reused. Four fibre washers are required for a complete set (two per union).
The banjo bolts should be tightened firmly but not over-torqued, as the soft fibre washers can be crushed to the point where the banjo eye distorts and the seal fails.
Blanking Plate
A blanking plate with gasket and two screws with spring washers seals the unused mechanical fuel pump aperture on the engine block. This casting feature is inherited from the C-series engine's Austin-Healey ancestry and was never used on the MGC, which has always been fitted with an electric pump. The blanking plate must seal correctly to prevent oil leakage from the crankcase.