The fuel pump in your car is responsible for managing the state of the fuel system between the gas tank and your diesel engine. Checking the fuel pressure of the pump is necessary when you think your car is not receiving an adequate amount of fuel depending upon your throttle positioning. Examine and determine this with a fuel pressure gauge.
Locate the marked fuel pressure test port on the fuel pressure rail of the engine. This should be visibly labeled, but if not, consult a repair manual for your model of diesel engine.
Attach the fuel pressure gauge to the test port.
Insert the key into the car and turn it to the "On" position. Record the fuel reading.
Start the car. The fuel pressure should remain the same as when the car was in the "On" position.
Tap the throttle. The fuel pressure gauge should shoot up by around 5 PSI. If it stays the same or drops, the fuel pressure in your fuel pump is incorrect and requires servicing.
