Bad Fuel Pump?
I would also measure the voltage at the fuel pump connector to see just what the voltage is. The process is as follows:
FUEL PUMP VOLTAGE TEST METHOD -FOUR PIN CONNECTOR
-Get a DMM and set it to VDC, highest A rating
-Backprobe the connector. On the four pin connector, the 12AWG RED wire is the one on the far right while the 12AWG BLK is on the far left side with the two inner wires for the sending unit.
NOTE: Tightly wrap a paper clip around each probe of your DMM. Wrap tape around at least one of either clip minus .250" / 1/4" to prevent SHORTING source.
NOTE: DO NOT REMOVE THE CONNECTOR DURING THIS TEST.
Insert the probes into the backside of the connector until you feel it mate up with the pin contact inside the cavity. RED goes to RED and Black goes to BLK.
NOTE: Ensure that probes are not going to short before running the test.
Have someone turn the KEY <ON> and note voltage to the pump. You will have ~2-3 seconds to obtain a reading. You should see ~12.XX volts at this time. NOTE: depending on what type of meter you are using, the meter may not be able to grab a reading in that amount of time. The use of either an analog meter or, a higher quality meter may be necessary to verify voltage.
<IF> full voltage is witnessed at the pump, you know it's getting voltage. If at this time, the motor is not spinning up, the most likely root cause is a failed FUEL PUMP motor. Another test to run here would be to find out what the current draw is once power is applied.
ACTION ITEM: R&R (remove and replace)
<IF> NO voltage is witnessed at the fuel pump, you've ether got no power TO the FUEL PUMP RELAY, either because, there's no source OR, the PCM has CUT power to the EFI system via opening the GROUND for the FUEL PUMP and ASD RELAYS respectively.
CM
TURN KEY <OFF> and remove DMM.
END OF TEST
FUEL PUMP VOLTAGE TEST METHOD -EIGHT PIN CONNECTOR
You may also have an eight pin connector and, if you do, the test is exactly the same other than the pin-out locations and wire colors. On the rear of the connector, there's only TWO 12 AWG wires and, they are in opposite corners / on a diagonal with, the HOT (+) being in the lower RIGHT corner and the NEG (-) in the upper LEFT corner. Now, this is from memory so, this MAY BE REVERSED as I can't recall for sure where HOT is.
CM
FUEL PUMP VOLTAGE TEST METHOD -FOUR PIN CONNECTOR
-Get a DMM and set it to VDC, highest A rating
-Backprobe the connector. On the four pin connector, the 12AWG RED wire is the one on the far right while the 12AWG BLK is on the far left side with the two inner wires for the sending unit.
NOTE: Tightly wrap a paper clip around each probe of your DMM. Wrap tape around at least one of either clip minus .250" / 1/4" to prevent SHORTING source.
NOTE: DO NOT REMOVE THE CONNECTOR DURING THIS TEST.
Insert the probes into the backside of the connector until you feel it mate up with the pin contact inside the cavity. RED goes to RED and Black goes to BLK.
NOTE: Ensure that probes are not going to short before running the test.
Have someone turn the KEY <ON> and note voltage to the pump. You will have ~2-3 seconds to obtain a reading. You should see ~12.XX volts at this time. NOTE: depending on what type of meter you are using, the meter may not be able to grab a reading in that amount of time. The use of either an analog meter or, a higher quality meter may be necessary to verify voltage.
<IF> full voltage is witnessed at the pump, you know it's getting voltage. If at this time, the motor is not spinning up, the most likely root cause is a failed FUEL PUMP motor. Another test to run here would be to find out what the current draw is once power is applied.
ACTION ITEM: R&R (remove and replace)
<IF> NO voltage is witnessed at the fuel pump, you've ether got no power TO the FUEL PUMP RELAY, either because, there's no source OR, the PCM has CUT power to the EFI system via opening the GROUND for the FUEL PUMP and ASD RELAYS respectively.
CM
TURN KEY <OFF> and remove DMM.
END OF TEST
FUEL PUMP VOLTAGE TEST METHOD -EIGHT PIN CONNECTOR
You may also have an eight pin connector and, if you do, the test is exactly the same other than the pin-out locations and wire colors. On the rear of the connector, there's only TWO 12 AWG wires and, they are in opposite corners / on a diagonal with, the HOT (+) being in the lower RIGHT corner and the NEG (-) in the upper LEFT corner. Now, this is from memory so, this MAY BE REVERSED as I can't recall for sure where HOT is.
CM
Last edited by cmckenna; Oct 26, 2010 at 11:34 AM. Reason: Forgot to include the eight pin pin-out config
