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TESTING

Navajo and B Series Pick-up Models

CAUTION
Fuel pressure must be relieved before attempting to disconnect any fuel lines.

The diagnostic pressure valve (Schrader valve) is located on the fuel supply manifold (rail). This valve provides a convenient point for service personnel to monitor fuel pressure, release the system pressure prior to maintenance, and to bleed out air which may become trapped in the system during pressure replacement. A pressure gauge with an adapter is required to perform pressure tests.

Fig. 1:Fuel pressure can be checked using an inexpensive pressure/vacuum gauge

If the pressure tap is not installed or an adapter is not available, use a T-fitting to install the pressure gauge between the fuel filter line and the throttle body fuel inlet or fuel rail.

To test the fuel pump, follow the accompanying diagnostic charts. Testing fuel pressure requires the use of a special pressure gauge (Ford Tool T80L-9974-B, Rotunda Fuel Pressure Testing Kit 014–00447, or equivalent) that attaches to the diagnostic pressure tap fitting. To perform the fuel system test a scan tool is necessary to access the different test modes.

NOTE: Depressurize the fuel system before disconnecting any lines.

Fig. 2:

Fuel pressure test chart–part 1

Fig. 3:

Fuel pressure test chart–part 2

Fig. 4:

Fuel pressure test chart–part 3

MPV Models
  1. Relieve the fuel system pressure and disconnect the negative battery cable.
  2. Disconnect the fuel line from the fuel filter outlet. Connect a fuel pressure gauge to the fuel filter outlet.
  3. Connect the negative battery cable. Connect the data link connector terminals F/P and GND (Ground) with a jumper wire.

    Fig. 5: Install a fuel pressure gauge to the outlet of the fuel filter

    Fig. 6: Connect a jumper wire between the F/P and GND terminals of the data link connector

  4. Turn the ignition switch ON to operate the fuel pump and check the fuel pressure. It should be 64–92 psi.
  5. If the fuel pressure is not as specified, replace the fuel pump.
  6. Turn the ignition switch OFF and disconnect the negative battery cable. Remove the jumper wire from the test connector.
  7. Remove the fuel pressure gauge and reconnect the fuel line to the fuel filter outlet.
  8. Connect the negative battery cable.

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