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Home >> Mazda >> 2002 >> B2300 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> System Tests >> Fuel Pressure Regulator
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Fuel Pressure Regulator

  1. Check Fuel Pressure

    Release fuel pressure. See FUEL PRESSURE RELEASE  . Start engine and idle. Disconnect fuel pressure regulator vacuum hose. Plug vacuum hose. Drive vehicle under heavy acceleration while a helper observes fuel pressure gauge. If fuel pressure holds steady within 3 psi (20.6 kPa), go to next step. If fuel pressure does not hold steady within 3 psi (20.6 kPa), check fuel vapor valve. If fuel vapor valve is okay, check for a plugged fuel filter. Repair as necessary.

  2. Check Fuel Pressure With Vacuum Applied To Regulator

    Connect vacuum pump to fuel pressure regulator. Apply vacuum to fuel pressure regulator. With engine idling, apply vacuum to fuel pressure regulator. Observe fuel pressure. If fuel pressure decreases when vacuum is applied, check vacuum hose and vacuum source. Repair as necessary. Go to next step. If fuel pressure does not decrease when vacuum is applied, replace faulty fuel pressure regulator. Go to step  4 .

  3. Check Fuel Pressure & Verify Fuel Flow

    Turn ignition off. Disconnect fuel return line from fuel rail. Connect a hose to fuel rail. Place opposite end of hose into a one quart container. With KOEO, connect scan tool to DLC. Using scan tool, select Output Test Mode. Press Mode to change to the ALL ON mode. Press Start to run fuel pump. Measure fuel line pressure and verify fuel is flowing into container. Turn ignition off. If fuel pressure is still high, replace faulty fuel pressure regulator. Restore vehicle. If fuel pressure is still not high, inspect fuel return line for blockage. Repair as necessary. Go to next step.

  4. Check Regulator For Fuel Leaks

    Start engine and idle for 10 seconds. Turn ignition off for 10 seconds. Start engine and idle for 10 seconds. Turn ignition off. Disconnect vacuum hose from fuel pressure regulator. Observe fuel pressure regulator for leaking fuel. If fuel pressure regulator is leaking fuel, replace faulty fuel pressure regulator. Restore vehicle. If fuel pressure regulator is not leaking, restore vehicle. Test is complete.
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