DISASSEMBLING A FUEL PUMP

1 Here we’re rebuilding a Bosch CP1 fuel pump. This particular unit was fitted to a first-generation Land Rover Freelander, built until 2006, but the pump type is used on a variety of makes and models.

2 As a diesel pump’s casing lives within a dirty engine compartment, it is imperative that all ports are plugged to prevent any contamination from entering the pump.

3 Carwood finds that degreasing and blast cleaning removes most of the deposits, but the unit is treated to a hot water and soap degrease afterwards, prior to being dried.

4 Only once the pump’s exterior casing is spotlessly clean should any dismantling take place, because fuel contamination is the main cause of high-pressure injection pumps failing internally.

5 First, the pressure control valve is removed – this is the only electrical component on this pump. Undo the two bolts holding it in place, extract the unit, discard the gasket and remove the end-seal (see inset pic).

6 Loosen all bolts that secure the head plate evenly, prior to unscrewing and storing them. As the plunger is spring-loaded, be wary of the assembly 'jumping' from its housing and landing on the floor.

7 Dismantle each head plate. From left to right is the plunger block, plunger, plunger spring, rubber head gasket, the combined inlet and outlet gate valve assembly, a steel high-pressure washer and the connector’s nylon and rubber washers.

8 When removing the steel high-pressure washer from the head, note how it locates onto the seat within the casting. The nylon and rubber seals can be levered-out carefully and discarded – do not scratch the aluminium surfaces.