Fuel Pump Relay: Testing and Inspection

Fuel Pump Relay (Circuit Open Relay):

^ Perform tests in order listed.

TEST 1 - RELAY SWITCHING FUNCTION CHECK

1. Disconnect relay from harness connector.

2. Apply 12 volts and ground to the relay terminals listed below and check for the correct result.

12V/Grnd - CORRECT RESULT
"STA"/"E1" - Energizes relay, connects terminals "B" and "Fp" (continuity).
"B"/"Fc" - Energizes relay, 12 volts becomes available at terminal Fp.

^ If results are not correct as described, replace relay.

TEST 2 - RELAY RESISTANCE CHECK

^ Check resistance between these relay terminals.

"STA"/"E1" - Resistance...21 - 43 ohms
"B"/"Fc" - Resistance...109 - 226 ohms
"B"/"Fp" - Resistance...infinite (no continuity)

^ If results are not correct as described, replace relay.

TEST 3 - RELAY CIRCUIT (WIRING) CHECK

^ Check voltage at the following terminals with relay installed, under these conditions.

3A - IGNITION "OFF"
No voltage at any terminal.

3B - IGNITION "ON" ENGINE NOT RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 0 volts
Terminal "Fc" - 12 volts


3C - IGNITION IN "START" POSITION (CRANKING)

Terminal "STA" - 12 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

3D - IGNITION "ON" ENGINE RUNNING

Terminal "STA" - 0 volts
Terminal "B" - 12 volts
Terminal "Fp" - 12 volts
Terminal "Fc" - 0 volts (or nearly zero)

NOTE: Relay terminal "E1" is a ground.

^ If voltage at any terminal is not correct, check wiring associated with that terminal.

^ If 12V is present at terminal "Fc" during engine cranking or engine running, and engine dies after starting, check for open in wiring between that terminal and air flow meter connector (Blue/Green wire). If wiring is OK, check fuel pump switch in air flow meter.

CHECKING FUEL PUMP SWITCH IN AIR FLOW METER

1. Remove air cleaner upper section.
2. Check for continuity between fuel pump relay harness connector terminal Fc and ground, while manually opening metering flap in air flow meter. Continuity should exist as soon as flap opens, and there should be no continuity when flap is closed.
3. If there is no continuity to ground with flap open, check for open in wire between fuel pump relay terminal Fc and air flow meter. Repair as necessary.
4. If wiring is OK, repair switch in air flow meter or replace meter.