Part 2

Flowchart A1-7 (2 of 2):

Fuel System Components:

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. Pressure but less than 280 kPa (40.5 psi) falls into two areas:

Regulated pressure but less than 280 kPa (40.5 psi). Amount of fuel to injectors OK, but pressure is too low. System will be lean running and may set Code 44. Also, hard starting cold and overall poor performance.

Restricted flow causing pressure drop. Normally, a vehicle with a fuel pressure of less than 165 kPa (24 psi) at idle will not be driveable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter.

2. Restricting the fuel return line allows fuel pressure to build above regulated pressure. With battery voltage applied to the pump test terminal, pressure should rise above 325 kPa (47 psi) as the valve in the return line is partially closed.

NOTE: Do Not allow pressure to exceed 414 kPa (60 psi), as damage to the regulator may result.


3. This test determines if the high fuel pressure is due to a restricted fuel return line or a pressure regulator problem.