3C-30 - FUEL SYSTEMS 90-824052R3 JUNE 2002
STEP 3: Perform voltage tests “all (1-6) engine
modes” below.
VOLTAGE TEST CHART
Engine Mode
BLACK Meter Lead to
Engine Ground; RED
Meter Lead to:
Approximate Voltage
Reading
If Approximate Voltage
is not obtained, this in-
dicates:
1. All models (+) terminal of fuel pump 12 – 13.5 volts If reading is below 12
volts, the battery is bad,
discharged or has bad
connection(s).
2. Ignition key in “OFF”
position.
(–) terminal of fuel pump. Same reading should be
obtained as reading in
check No. 1 (above)
If reading is lower than in
check 1, the ECM is bad.
3. Ignition key in “ON”
position and engine
NOT running.
(–) terminal of fuel pump. 2 volts or less (voltage
should rise to 12 – 13.5
volts after approximately
30 seconds.
Bad ECM or bad fuel
pump*.
4. Engine being cranked. (–) terminal of fuel pump. 2 volts or less. Bad ECM or bad fuel
pump.
5. Engine running below
approximately 2000
RPM.
(–) terminal of fuel pump. 2 volts or less (for
approximately 30 se-
conds and then switch to
approximately 5 volts.
Bad ECM or bad fuel
pump.
6. Engine running above
approximately 2000
RPM.
(–) terminal of fuel pump. 2 volts or less. Bad ECM or bad fuel
pump.
*Check for proper electrical operation of electric fuel
pump. (Step 4)
STEP 4: Disconnect RED/PURPLE wire to nega-
tive terminal on electric fuel pump. Con-
nect a ground jumper wire from negative
pump terminal to a good engine ground.
Results: Pump does not operate. Replace electric
fuel pump.
Pump operates. But, pressure reading does not
change when performing electric fuel pump “pres-
sure” test. Replace electric fuel pump.
Pump operates. Check RED/PURPLE (–) lead and
harness for good continuity.
NOTE: RED/PURPLE lead is connected to pin 2 of
EFI harness.
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