K 1500 Yukon Denali AWD V8-6.0L VIN U (2002)
Steps 19-25
The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the fuel pump is operating.
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.
6. This step tests the fuel pressure regulator. The fuel pressure regulator is controlled by the engine vacuum. With the engine vacuum applied, the
pressure should drop to the specified value.
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 the fuel
pump is commanded ON, replace the fuel pressure regulator.
10. This step tests for a loss of fuel pressure between the fuel feed pipe shut-off adapter and the fuel pump.
11. This step tests for a leaking fuel injector or for a leaking fuel pressure regulator. If the fuel pressure remains constant during this test, the fuel
injectors are not leaking fuel.
14. This step tests for a restricted fuel return pipe. If the fuel pressure is within the specified values, there is a restriction in the fuel return pipe.
16. This step determines if the fuel pressure regulator or the fuel pump is the cause of the low fuel pressure. If the pressure rises above the specified
value, the fuel pump is OK.
18. This step verifies that a circuit condition is not the cause of a fuel pressure concern. Thoroughly inspect all fuel electrical circuits.
