For undertaking the fuel pressure test get a fuel pressure gauge coupled with a fuel injection system adapter. Start with a visual inspection performing a rundown check with fuel on the tank, check at the threaded ends of the fuel line for leaks while the engine is running; check for tight connections, flatten or kinks of hoses. Following this, release the fuel system pressure. For models with port fuel injection as required, position the gauge over the Schrader valve of the fuel rail, turn the ignition ON with the Aircon OFF, and take the reading when the fuel pump has its cycle for 2 seconds. The pressure should be maintained constant to the values available within the set range. Switch on the engine for some time and allow it to warm; the pressure should reduce by 3-10 psi. If it does not then add 10 inches vacuum to the pressure regulator and look for pressure drop to know if the regulator needs repair or replacement. If pressure is not within specs consult fuel filter & hoses, pressure regulator, fuel line for leaks & the in-tank fuel pump check valve. Upon completion of the test, turn off the fuel pump and then, switch off the ignition to relieve fuel pressure and then unscrew the gauge. For models with
Throttle Body injection, turn the ignition off for at least twenty seconds, release the fuel pressure, connect a fuel pressure gauge between the fuel hose and the throttle body inlet and use a fused jumper wire when testing the pressure. If the pressure is within the requirements, then no more test is required if not then look for restricted lines or problem with the regulator. After that, it is required to turn off the fuel pump, release fuel pressure, and, finally, take out the gauge. If there are suspicions that there are problems with the fuel pump, check whether you can hear the noise at the moment when the switch is turned On and during the start of the engine. If the pump does not activate, then look at the fuse and the relay of the fuel pump on your car. To test the relay unscrew it while the engine is on; in case the engine continues to run then the oil pressure switch may be a problem. Connect back the relay and touch the terminal for fuel pump with a test light to check the circuit.