Part 2 of 3

Chart A-7 - Fuel System Diagnosis (Part 2 Of 3):

Fuel Line Diagram:

Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
5. Fuel pressure that drops off during acceleration, cruise or hard concerning may cause a lean condition and result in a loss of power. surging or misfire. This condition can be diagnosed using a Tech 1 scan tool. If the fuel system is very lean, the oxygen sensor will stop toggling and output voltage will drop below 500 mV. Also, injector pulse width will increase,

Important: Make sure system is not operating at "Fuel Cut-off" which may cause false readings on the scan tool.

6. Fuel pressure below 284 kPa (41 psi) may cause a lean condition and may set a DTC 44. Driveability conditions can include hard starting cold, hesitation, poor driveability, lack of power, surging or misfire.
7. Restricting fuel flow as directed causes fuel pressure to build above regulated pressure. With battery voltage applied the pump "test" connector, pressure should rise above 325 kPa (47 psi) as the gage outlet hose is pinched.

NOTICE: Do not allow pressure to exceed 414 kPa (60 psi), as damage to the fuel system components or pressure gage may result.

8. Fuel pressure above 325 kPa (47 psi) may cause a rich condition and may set a DTC 45. Driveability conditions can include hard starting (followed by black smoke) and a strong sulfur smell in the exhaust.
9. This test determines if the high fuel pressure is due to a restricted fuel return line or a faulty fuel pressure regulator.
10. The pressure regulator filter screen is designed to trap any contaminants introduced during engine assembly. If dirty, it can be removed with a small pick and discarded without potential harm to the regulator.