MG Tech – MGB Fuel Pump Replacement

It is not an uncommon sight to see an MGB owner lying on the ground hitting the underside of their car for no apparent reason – this was a procedure that Area Secretary Graham Lowe was caught doing recently and eventually resulted in a visit to Roger Taylor.

The usual explanation, as in this case, is a faulty fuel pump that can be coaxed back into life, if all be it temporary, with a swift clout from a spanner.

Being housed in an exposed position under the car (rubber bumper models had the pump relocated inside the boot) means that the fuel pump is vulnerable to both damage and corrosion and eventually it is going to reach the end of its useable life.

Because of its location under the car, replacing the fuel pump is best done using a car lift to raise it to a workable height. If you don’t have access to one then use ramps or axle stands, but make sure they are properly positioned and secure.

First task is to remove the near-side rear wheel to gain easier access to the pump. Cover the exposed spline or hub to avoid getting greasy.

Next, disconnect the unions and breather pipe, loosen the pump bracket (normally two bolts) and remove the pump, being careful with the electrical connections. You will need to retain the rubber support ring from the body of the old pump for fitting onto the new pump.

With the pump removed, check the rubber fuel hose as this can be worn and damaged – if it has been on there for the same length of time as the pump it is probably a good idea to replace with a modern rubber fuel hose. The same goes for the electrical connectors which can be renewed if required and as a tip always use new washers for the banjo connections when changing the pump.

Check the metal fuel pipe which runs from the pump to the engine compartment – If heavily corroded it is best to replace it.

While under the car check the metal pipe which runs from the petrol tank to the pump, if in doubt renew this as well. This is a ready manufactured item with swaged connections at each end. If you have a leak in this pipe it introduces air into the fuel system and changes the mixture.

Before fitting the new fuel pump take careful note of the position of the inlet and outlet points (marked TOP and OUT).

When locating the new pump ensure that you connect the breather pipe and the electrical connections securely and tighten the bracket in place. Finally, make sure that the unions are really tight and refit the new rubber fuel pipe.

A replacement fuel pump costs around £92, fuel pipe will set you back £20 and allow £10 for additional pieces of hose and securing clips. Replacing a fuel pump should take about an hour for a skilled mechanic.