If fuel pressure is zero or low, with ignition off, ensure inertia switch is set. Ensure battery is fully charged. Using a jumper lead, ground FP lead terminal of self-test connector. See Fig 1 . Inertia switch is located under dash to the right of transmission tunnel. With ignition on, engine off and inertia switch electrical connector connected, check voltage at fuel pump inertia switch. If voltage is 10.5 volts or more at both inertia switch terminals, go to step 3).
If voltage is 10.5 volts or more at only one inertia switch terminal, replace inertia switch. If voltage is less than 10.5 volts at both inertia switch terminals, check and repair wiring circuit.
With ignition off, ensure connection is okay at pump/sender unit. Turn ignition on, with engine off. Listen for sound of fuel pump operation. If pump is not running, go to next step. If pump is running, check condition of fuel filter. If filter is okay, replace fuel pump. If filter is dirty, replace filter and recheck system.
Turn ignition off and disconnect fuel pump/sender connector. See Fig 1 . Turn ignition on, with engine off. Measure voltage at pump power terminal (Pink/Black wire) of pump/sender connector. If voltage is 10.5 volts or more, go to next step. If voltage is not 10.5 volts or more, repair open in Pink/Black wire between fuel pump and inertia switch.
With fuel pump/sender connector still disconnected, measure resistance of pump ground wire (Black wire) to chassis ground. See Fig 1 . If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, repair open in Black wire between fuel pump and ground.
Turn ignition off. Measure resistance between inertia switch and ground. If resistance is less than 5 ohms, replace fuel pump. For additional circuit testing information see CIRCUIT TEST J in TESTS W/CODES - NAVAJO article.

Fig 1: Identifying Fuel Pump & Self-Test Connectors (Navajo)

Courtesy of MAZDA MOTORS CORP.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Fuel Pump Circuit (Navajo)

Use the Manual With the Right Hardware

When to See a Mechanic