Cherokee 2WD L4-150 2.5L VIN P MFI (1991)
fusible links and supply voltage from the battery. If voltage is present proceed to step 2.
2.
Connect the voltmeter to the A141 (terminal 87) wire at the fuel pump relay connector. Turn the ignition key to the START position and crank the
engine. If output voltage is present during cranking, for approximately 2 to 3 seconds, the fuel pump relay is functioning normally and no further
testing of the ASD relay is necessary. If no voltage is present at the A141 wire, proceed to step 3.
3.
Connect the voltmeter to the Dk. Blue A21 (terminal 86) wire at the fuel pump relay connector. Turn the ignition key to the RUN position. Input
voltage from the SBEC II to the fuel pump relay should be present, for approximately 2 to 3 seconds. If voltage is present proceed to step 4. If no
voltage is present, connect an ohmmeter between the Dk. Blue A21 wire (terminal 86) and terminal No. 9 (Dk. Blue wire) at the SBEC II, and
check for continuity. If continuity exists, the problem is computer related.
If no continuity exists, repair open in wire and retest the operation of the ASD relay.
4.
Connect voltmeter to the orange/green K51 wire (terminal 85) at the fuel pump relay connector. Turn ignition key to ON position, while
observing voltage at K51. Voltage should be present at K51 and drop to less than 1 volt once the ignition switch is turned to the START position
(voltage will only remain at 0 for approximately 2 seconds). If voltage drops, fuel pump relay is functioning, and no further testing of the fuel
pump relay is necessary. If voltage does not drop, the problem is computer related.
If no voltage is present, disconnect the fuel pump relay, and connect an ohmmeter between the K51 (terminal 85) and A21 (terminal 86) of the fuel
pump relay and check for continuity. If no continuity exists, replace the fuel pump relay and test operation.
5.
If the ASD and fuel pump relay are functioning properly and the fuel pump is still inoperative, test the ballast bypass relay and ballast resistor.
