Fuel pressure — check
Warning: Gasoline is extremely flammable.
Note: The following procedure assumes that the fuel pump is receiving voltage and runs.
Note: In order to perform the fuel pressure test, you will need to obtain a fuel pressure gauge capable of measuring high fuel pressure and the proper adapter set for the specific fuel injection system.
1. Relieve the fuel system pressure (see Fuel pressure relief procedure). Disconnect the fuel line from the fuel rail, then use the proper adapter to connect the pressure gauge between the fuel line and fuel rail (see illustrations).
4.1a This fuel pressure testing kit contains all the necessary fittings and adapters, along with the fuel pressure gauge, to test most automotive fuel systems
4.1b Attach the fuel pressure gauge between the two sides of the quick- connect fitting; turn the ignition key ON and check the fuel pressure
2. Turn all the accessories Off and switch the ignition key On. The fuel pump should run for about two seconds; note the reading on the gauge. After the pump stops running, the pressure should hold steady. After five minutes it should not drop below the minimum listed in this Chapter’s Specifications.
3. Start the engine and let it idle. The pressure should remain the same. If all the pressure readings are within the limits listed in this Chapter’s Specifications, the system is operating properly.
4. If the fuel pressure is not within specifications, check the following:
- ) If the pressure is higher than specified, replace the fuel pressure regulator (see Fuel pressure regulator — removal and installation).
- ) If the pressure is lower than specified, check the fuel filter and fuel lines from the fuel rail to the fuel tank for restrictions or damage. Check the fuel injectors for leaks. If the pressure is still low, most likely the fuel pressure regulator and/or the fuel pump is defective. In this situation, it is recommended that both the fuel pressure regulator and fuel pump are replaced to prevent any future fuel pressure problems.
5. After the testing is done, relieve the fuel pressure (see Fuel pressure relief procedure) and remove the fuel pressure gauge.