Problems in fuel systems using electric fuel pumps are usually indicated by improper fuel system pressure or a dead or inoperative fuel pump. Fuel pressure is read with a fuel pressure gauge.
Fuel Pump Test for Engines with Fuel Injection
These photos outline the steps to follow while performing the test on an engine with fuel injection.
Many problems on today's cars can be caused by incorrect fuel pressure. Therefore, checking fuel pressure is an important step in diagnosing driveability problems.
Prior to testing the fuel pump, a careful visual inspection of the injectors, fuel rail, and fuel lines and hoses is necessary. Any sign of a fuel leak should be noted and the cause corrected immediately.
The supply line into the fuel rail is a likely point of leakage. Check the area around the fitting to make sure no leaks have occurred.
Most fuel rails are equipped with a test fitting that can be used to relieve pressure and to test pressure.
To test fuel pressure, connect the appropriate pressure gauge to the fuel rail test fitting (Schrader valve).
Connect a hand-held vacuum pump to the fuel pressure regulator.
Turn the ignition switch to the RUN position and observe the fuel pressure gauge. Compare the reading to specifications. A reading lower than normal indicates a faulty fuel pump or fuel delivery system
Art courtesy of Delmar - Thomson Learning.
To test the fuel pressure regulator, create a vacuum at the regulator with the vacuum pump. Fuel pressure should decrease as vacuum increases. If pressure remains the same, the regulator is faulty.