Fuel Pump: Testing and Inspection

Fuel Pressure Check - Part 1 Of 2:

Fuel Pressure Check - Part 2 Of 2:

Fuel Pressure Check:

Circuit Description:
When the ignition switch is turned to the "START" position, the circuit opening relay will be 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. The fuel pump delivers fuel to the fuel rail where the pressure is maintained by the fuel pressure regulator at 284 kPa (41 psi) higher than the pressure inside the intake manifold. Excess fuel is returned to the fuel tank through a return pipe and hoses.

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

1. This measures the fuel pressure with the ignition switch in "ON."

2. This determines if the fuel pressure is normal.

3. This checks for a leaking fuel pressure regulator.

4. This checks for plugged fuel injectors.

5. This checks for leaking fuel injectors or a leaking fuel pump.

6. This checks for a leaking fuel pressure regulator or fuel pump.

Diagnostic Aids:
Check for leakage around all fuel hose/pipe connections.

A plugged fuel injector could he the cause of a hard/no-start condition or loss of power/poor fuel economy.