The correct functioning of the fuel system in a diesel engine is extremely important in order to take full advantage of the power of the drivetrain and also to increase its lifetime. Faultless functioning of the system is also responsible for the optimum consumption. In older cars, failures of the injection pump are quite common. This is experienced as a considerable drop in power. Another symptom might be starting issues. This is a clear signal which should prompt you to have the functioning of the injection pump checked.