Test Description

The numbers below refer to step numbers in diagnostic procedure.

1. 2
   
   This step verifies fuel pump is operating.
2. 4
   
   This step tests for an internal fuel leak. If fuel pressure decreases during this test, then an internal loss of pressure is indicated.
3. 7
   
   This step inspects fuel pressure regulator for a fuel leak from atmospheric vent. If fuel leaks from fuel pressure regulator while fuel pump is commanded ON, replace fuel pressure regulator.
4. 8
   
   This step tests for a loss of fuel pressure between shut-off adapter on fuel feed pipe and fuel pump.
5. 9
   
   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.
6. 12
   
   This step tests for a restricted fuel return pipe. If fuel pressure is within specified values, a restriction in fuel return pipe is indicated.
7. 14
   
   This step determines if fuel pressure regulator, or fuel pump, is cause of low fuel pressure. If pressure rises above specified value, fuel pump is okay.
8. 16
   
   This step verifies that a circuit condition is not cause of a fuel pressure concern. Inspect all fuel pump electrical circuits thoroughly.