Replacing a fuel pump in a diesel engine involves several steps, and the process can vary slightly depending on the vehicle or machinery. On average, replacing a diesel fuel pump costs between $400 and $1,000, depending on the brand and labor rates in the region. First, disconnect the battery to ensure safety. Then, drain the fuel tank of any remaining diesel fuel, which can be done with a siphon pump or by disconnecting the fuel line and allowing the fuel to drain into a container. In some models, the fuel tank will need to be completely removed in order to access the fuel pump. On some diesel engines, the fuel pump may be reached after other components, like an intake manifold or air filter assembly, are removed.
The fuel pump itself can then be found once the tank is removed or accessed. On some diesels, the fuel pump is mounted on the engine while others may have it submerged in the fuel tank. For an engine with the fuel pump outside of the fuel tank, remove the mounting bolts, and disconnect the fuel lines; this can require some specific tools, such as a fuel line disconnect tool. Whenever working around the fuel system, basic safety equipment is required to protect against potent fumes and splashes from fuel.
Change the old pump with a new, compatible unit suitable for this particular diesel engine. Diesel fuel pumps carry different specifications on pressure, varying between 500 and 2,000 PSI per the engine model. If a pump is installed with the wrong pressure rating, poor engine performance or damage to the engine may result. After installation of the new pump, all fuel connections should be checked for proper tightening. When everything is reassembled, the tank can be filled with fresh diesel fuel, the battery reconnected, and the system tested. The engine should start with ease and the pump should provide sufficient fuel pressure to the injectors.
More often than not, there are additional steps for bleeding the fuel system in order to remove air pockets, such as in most of the older diesel engines. Bleeding the system ensures that fuel reaches the injectors at proper pressure to avoid misfiring or rough idling. Restoring the pressure through a process called “priming” may be required by cycling the operation of the engine or with a manual primer pump on some vehicles.
Proper replacement of the Fuel Pump in a diesel engine, since an unreliable pump leads to fuel starvation, or poor performance, or eventually to engine failure. The overall time required for the entire process of removal and installation of a pump usually ranges from 3 to 6 hours or so, depending on the type of engine and intricacy in the design of the fuel system.