Fuel Pressure: Testing and Inspection

The following tests can be used to determine if the fuel pump is operating properly.




All 1982---83 Models;
1984---85 Crown Victoria, Grand Marquis & Town Car

1. Check for adequate supply of fuel.
2. Check for fuel leakage at all lines and fittings.
3. Check continuity to fuel pump as follows:
a. Disconnect electrical connector just forward of fuel tank, then connect a voltmeter to body wiring harness connector.
b. Turn ignition key to ``On'' while observing voltmeter. Voltmeter should indicate battery voltage, then return to zero after one second.
c. Turn ignition switch to Start position momentarily while observing voltmeter. Voltmeter should indicate approximately eight volts while cranking.
d. If voltages are not as specified, check electrical system and make necessary repairs.
4. Check fuel pump operation as follows:
a. Disconnect return fuel line at throttle body, then connect hose from throttle body fitting to a calibrated container of at least 1 quart capacity.
b. Connect pressure gauge T80L-9974-A or equivalent to fuel diagnostic valve on fuel charging assembly.
c. Disconnect electrical connector to fuel pump just forward of fuel tank, then connect an auxiliary wiring harness to fuel pump connector.
d. Energize pump for 10 seconds by connecting auxiliary wiring harness to a fully charged 12 volt battery. Observe pressure while pump is energized.
e. Allow fuel to flow into container while observing capacity. The fuel pressure reached should be 35---45 psi and the fuel capacity should be a minimum of 1/3 quart in 10 seconds. Fuel pressure should remain steady at 30 psi immediately after de-energizing the fuel pump. The fuel pump is operating normally if the above conditions are met.
f. If specified pressure in step 4(e) is obtained, but volume is below specifications, check for obstructions in fuel filters or supply lines. After making the necessary corrections, repeat steps d and e. If fuel volume is not as specified, replace pump.
g. If specified volume in step (e) is obtained, but pressure is below specifications, check for damaged or worn pressure regulator.
h. If both pressure and volume are as specified in step e, but pressure is not maintained after de-energizing, check for leaking injector valve and/or pressure regulator. If both are satisfactory, replace fuel pump.