Diaphragms for Lift Pumps

The diaphragm is an important component in your engine's fuel lift pump system.

The diaphragm not only draws the fuel from the tank, but it prevents engine oil from being contaminated with diesel fuel and stops air getting into the system.

Typically, the coatings used on the diaphragms of lift pumps are neoprene and PTFE. Diesel fuel is continually in contact with the diaphragm so the coating has to be resistant to corrosion from the diesel fuel. The coating obviously also needs to be very flexible and to be able to cope with the continual movement that is associated with its use.

If the oil level is rising mysteriously this can be a sign that the lift pump diaphragm has failed and needs to be replaced immediately. Another sign of failure is fuel mixed in with the engine oil, this is very likely the reason why the oil level has been rising. One option is to replace the lift pump entirely, but this may not always be necessary. To save this expense, and if you have the necessary skills of a mechanic available to you, you could replace the lift pump diaphragm unit.

This involves disassembling the pump replacing the diaphragm and rebuilding the pump. It’s a skilled job and Mechanics often need a small 'C' clamp to squeeze the diaphragm and plunger together when reassembling the unit.

At Darwen Diesels we have an excellent range of both single and double U, V, VP and Y type diaphragms covering almost every type of lift pump out there. If, however, you do have a problem finding the lift pump diaphragm you need, then please do not hesitate to call our sales and service team. Our technical advisors will be happy to help you source the part in question if they can.