1 The most common mechanical issue with a diesel injection pump is the rotor seizing in the distributor section of the diesel pump. In most cases this is caused by the diesel pump failing to get lubrication caused by a clog. The diesel injection pump uses the fuel as the lubricant.

2 Air getting into any of the fuel lines of a diesel injection pump will cause a loss of fuel pressure. Most diesel injection pumps are not self priming; therefore air getting into the fuel system will cause problems in starting the diesel engine or stall the engine once it has started.

3 In almost all diesel Injection pumps the computer was not part of the original design. Therefore the cylinders in which the computers control to regulate fuel flow are potentially not in optimized locations. In some diesel injection pump models that are now driven by computers the connections between the circuit board to the computer can become corroded. Often times these types of issues with pumps occur when the connections are made on the bottom of the diesel injection pump and insufficient protection is provided.

4 Clogging of diesel Injectors occurs over time and typically requires an injector overhaul every 100,000-150,000. Routinely checking and changing fuel filters can increase the mileage and life of diesel injectors.

5 If the sylinator that functions to remove water from the diesel fuel system is not performing then water contaminates the fuel supply causing poor engine performance, stalling or even the inability to start the engine.

6 Clogged fuel filter will not allow the diesel injection pump to gain access to the fuel it needs in order to keep the engine running.

7 The diaphragm of the diesel lift pump can rupture causing the eventual failure of the diesel fuel injection pump. Once the diaphragm ruptures the piston vibrate which rapidly wears down the piston and eventually causes the fuel to bypass the pump. Low or no fuel pressure is the result.

8 The diesel injector pump can lose its calibration and need to be sent to a manufacturers service center for recalibration, although this is typically diagnosed as the problem in relatively new equipment.

The accurate way and often times the only way to test a diesel pump is under load. The majority of the time the diagnosis is that the pump needs to be rebuilt or discarded. Therefore most sales of diesel fuel injection pumps, due to high value and time constraints placed upon the piece of equipment that is out of service requires a core to be traded for the new pump. This way the service center can make a determination as to what the problem is and rebuild the pump over the period of a few weeks, and then place the rebuild diesel injection pump back into service.