Chart A-7 Fuel System Diagnosis

Fig. 028 - Wiring Diagram for Chart A-7 Fuel System Diagnosis. VIN J:

CHART A-7

FUEL SYSTEM DIAGNOSIS

1.8L "J" SERIES
FUEL INJECTED (PORT)

When the ignition switch is turned "ON", the Electronic Control Module (ECM) will turn "ON" the in-tank fuel pump. It will remain "ON" as long as the engine is cranking or running, and the ECM is recieving HEI distributor reference pulses.
If there are no reference pulses, the ECM will shut "OFF" the fuel pump within 2 seconds after key "ON" or engine stopped.
The pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator, where the system pressure is controlled to 179 to 317 kPa (26 to 46 psi). Excess fuel is then returned to the fuel tank.

Fig. 027 - Chart A-7 Fuel System Diagnosis.:

1. Use a pressure gage. Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when installing the gage.

With 12 volts applied to the pump test terminal located left side of engine compartment, the in-tank fuel pump should run and pressure established within a few seconds. Removing the jumper will stop pump. Pressure should drop 21-41 kPa (3-6 psi) and hold steady.
2. When the engine is idling, the manifold pressure is low (high vacuum) and is applied to the fuel regulator diaphragm. This will offset the spring and result in a lower fuel pressure by 21-41 kPa (3-6 psi). This idle pressure will vary somewhat depending on barometric pressure, however, the pressure idling was less indicating pressure regulator control.

Turbo boosted pressure will increase fuel pressure about one pound for each pound of manifold boost up to approximently 317 kPa (46 psi) max. fuel pressure. This can be simulated by applying pressure to the fuel regulator using a low pressure air pump.
3. Pressure that continues to fall is caused by one of the following:
a. In-tank fuel pump check valve not holding.
b. Pump coupling hose leaking.
c. Fuel pressure regulator valve leaking.
d. Injector sticking open.

Fig. 029 - Chart A-8 Fuel System Diagnosis.:

Fig. 030 - Wiring Diagram for Chart A-8 Fuel System Diagnosis. VIN J:

CHART A-8,

FUEL SYSTEM DIAGNOSIS

1.8L TURBO "J" SERIES
FUEL INJECTION (PORT)

1. Pressure but. less than 207kPa (30 psi) falls into two areas:
a. Regulated pressure but less than 30 psi (207 kPa) - Amount of fuel to injector OK but pressure is too low. System will be lean running and may set Code 44. Also, hard starting cold and overall poor performance.
b. Restricted flow causing pressure drop - Normally, a vehicle with a fuel pressure of less than 62 kPa (9 psi) at idle will not be driveable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop as pressure begins to drop rapidly.
2. Restricting the the fuel return line allows the fuel pump to develop its maximum pressure (dead head pressure). When battery voltage is applied to the pump test terminal, pressure should be above 60 psi (414 kPa).
3. This test determines if the high fuel pressure is due to a restricted fuel return line or a pressure regulator problem.