The Porsche 944 was built until 1991. It was produced with a 3.0 liter inline four cylinder engine and came standard with many different features, including power brakes, a power sunroof, cruise control, air conditioning, power windows, a five-speed manual transmission and four wheel anti-lock brakes. It was also equipped with an electric fuel pump that sits inside the car's fuel tank and sends fuel from the gas tank to the engine. By properly troubleshooting the fuel pump you may find that another fuel system component is faulty and save yourself the time it would have taken to access and replace the pump.
Watch for your Porsche to exhibit symptoms of a failed fuel pump. The two primary symptoms of a bad fuel pump is the Porsche failing to start when you turn the ignition key and the engine stalling when you push down on the accelerator pedal to increase the Porsche's speed.2
Make sure the fuel pressure is in the proper range. Connect a fuel pressure gauge to the Schrader valve of your car. The Schrader valve looks very similar to a air nozzle on a bicycle or car tire and is located at the top of your engine. Once you have connected the fuel pressure gauge to the valve, turn your Porsche on and let the engine idle. Read the gauge to see if the fuel pressure is within an acceptable range. The proper fuel pressure range for a 1991 Porsche 944 is 46 to 51 pounds per square inch.3
Check to see if the fuel pressure regulator is causing your fuel system problems instead of a faulty fuel pump. If your Porsche has low fuel pressure the fuel pressure regulator may be at fault instead of the fuel pump. With the fuel pressure gauge still attached to the Schrader valve, find the fuel pressure regulator, which is near the Schrader valve, and gently squeeze the fuel line running to the regulator while the Porsche's engine is idling. If the fuel pressure gauge shows the car's fuel pressure increasing as you squeeze the fuel line the regulator is bad and should be repaired or replaced.4
Make sure the fuel pump begins working when the battery begins to work. The fuel pump should begin pulling gas from the fuel tank as soon as the battery of the car starts energizing. Turn your ignition key one notch to the right so that the battery is on but the Porsche's engine is not. Sit and listen for the fuel pump. You should be able to hear it working if it is still functioning properly. You will need to perform this test in a quiet place or you may need a second individual to help you listen for the pump.