Chart A1-7A Fuel System Circuit Opening Relay Check

Fuel System Circuit Opening Relay Check - Part 1 Of 2:

Fuel Circuit Opening Relay Check - Part 2 Of 2:

Fuel System Circuit:

Circuit Description:
When the ignition switch is turned to the "START" position, the circuit opening relay will he energized to allow the fuel pump to operate to pressurize the system. The fuel pump will continue to operate if the engine control module (ECM) receives an ignition signal when the engine is started. The fuel pump operates as long as the circuit opening relay is energized by the ECM. When the circuit opening relay is de-energized, the fuel pump will stop operating.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This checks for normal fuel pump operation.

2. This checks to see if the fuel pump will run when DLC terminals "+B" and "FP" are jumpered together.

3. This checks fuel pump operation while the ignition signal is present at the ECM.

4. This checks for an open in BLK/RED wire to circuit opening relay.

5. This checks for an open in BLK/RED wire to DLC.

6. This checks for an open BLU/BLK or GRN/RED wire, a faulty ECM or for a faulty circuit opening relay.

7. This checks for an open WHT/BLK or BLU/BLK wire, or for a faulty fuel pump.

Diagnostic Aids:
A restricted or leaking fuel feed pipe or hose will cause an "Engine Cranks But Will Not Run" condition. Check fuel sender assembly connections inside of fuel tank for poor connections. Refer to Chart A1-7B for fuel pressure test.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect hamess connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.