Safari Van AWD V6-262 4.3L VIN W CPI (1992)
Fuel Pump Relay Circuit
Circuit Description:
When the ignition switch is turned "ON," the 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 receiving distributor reference pulses. If there are no reference pulses, the ECM will shut "OFF" the fuel pump within 2
seconds after ignition "ON" or engine stops.
The pump will deliver fuel to the TBI unit where the system pressure is controlled to about 62 to 90 kPa (9 to 13 psi). Excess fuel is then returned
to the fuel tank.
The CPI pump will deliver system pressure that is controlled to about 370-440 kPa (54-64 psi). Excess fuel is then returned to the fuel tank.
Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Turns "ON" the fuel pump if CKT 120 wiring is OK. If the pump runs, it maybe a fuel pump relay circuit problem, which the following steps
will locate.
2. The next two steps check for power and ground circuits to the relay.
3. Determines if ECM can control the relay.
4. The oil pressure switch serves as a backup for the fuel pump relay to help prevent a "no start" situation. If the fuel pump relay was found to be
inoperative, the oil pressure switch circuit should also be tested to determine why it did not operate the fuel pump.
