Test Description

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

1. 2
   
   This step verifies that fuel pump is operating.
2. 4
   
   This step tests for an internal fuel leak. If fuel pressure drops during this test, an internal loss of pressure is indicated.
3. 6
   
   This step tests fuel pressure regulator. Fuel pressure regulator is controlled by engine vacuum. With engine vacuum applied, pressure should drop specified value.
4. 9
   
   This step inspects fuel pressure regulator for a fuel leak from vacuum port. If fuel leaks from 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 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 specified values, a restriction in fuel return pipe is indicated.
8. 16
   
   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.
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.