Test Description

The numbers below refer to step numbers in the diagnostic procedure.

1. 2 -  This step verifies that the fuel pump is operating.
2. 4 -  This step tests for an internal fuel leak. If the fuel pressure drops during this test, then an internal loss of pressure is indicated.
3. 6 -  This step tests the fuel pressure regulator. The fuel pressure regulator is controlled by engine vacuum. With engine vacuum applied, pressure should drop the specified value.
4. 9 -  This step inspects the fuel pressure regulator for a fuel leak from the vacuum port. If fuel leaks from the fuel pressure regulator while fuel pump is commanded ON, replace fuel pressure regulator.
5. 10 -  This step tests for a loss of fuel pressure between the fuel feed pipe shut off adapter and fuel pump.
6. 11 -  This step tests for a leaking fuel injector or fuel pressure regulator. If fuel pressure remains constant during this test, fuel injectors are not leaking fuel.
7. 14 -  This step tests for a restricted fuel return pipe. If fuel pressure is within the specified values, a restriction in the fuel return pipe is indicated.
8. 16 -  This step determines if fuel pressure regulator or fuel pump is the cause of the low fuel pressure. If pressure rises above the specified value, fuel pump is okay.
9. 18 -  This step verifies that a circuit condition is not the cause of a fuel pressure concern. Inspect all fuel pump electrical circuits thoroughly.