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Home >> Mazda >> 2006 >> B3000 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> Fuel System >> Fuel System Pressure Test Procedure >> Fuel Pressure Regulator Inspection
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Fuel Pressure Regulator Inspection

  1. Check Fuel Pressure

    Release fuel pressure. Install Fuel Pressure Gauge (49-UN01-010). Start engine and run at idle. Disconnect vacuum hose from fuel pressure regulator and plug it. Drive vehicle under heavy acceleration while observing fuel pressure gauge reading. If fuel pressure holds steady within 3 psi (20.6 kPa), go to next step. If fuel pressure does not hold to within 3 psi (20.6 kPa), check fuel vapor valve. If fuel vapor valve is okay, check for clogged fuel filter.

  2. Check Fuel Pressure With Vacuum Applied To Regulator

    Connect vacuum pump to fuel pressure regulator. Apply vacuum to fuel pressure regulator. If fuel line pressure decreases when vacuum is applied, check vacuum hose and vacuum source. Repair as necessary. After repair, go to next step. If fuel pressure does not decrease when vacuum is applied, replace fuel pressure regulator. After repair, go to step  4.

  3. Check Fuel Pressure And Verify Fuel Flow

    Disconnect fuel return line from fuel rail. Connect a short hose from fuel rail to a one quart (one liter) measuring container. Turn ignition on, engine off. Connect scan tool to DLC. Select DIAGNOSTIC DATA LINK. Select PCM. Select ACTIVE COMMAND MODE. Select OUTPUT TEST MODE and FUEL PUMP PID. Press MODE to change to ALL ON MODE. Press START to run fuel pump. Measure fuel line pressure and verify fuel is flowing into container. If fuel pressure is still high, replace fuel pressure regulator. Restore vehicle to original condition. If fuel pressure is not high, inspect fuel return line for blockage or clog. Repair or replace as necessary. After repair, go to next step.

  4. Check Regulator For Fuel Leaks

    Start engine and run at idle for 10 seconds. Turn ignition off for 10 seconds. Start engine and run at idle for 10 seconds. Turn ignition off. Disconnect vacuum hose from pressure regulator. If diaphragm is leaking fuel, replace fuel pressure regulator. Restore vehicle to original condition. If fuel is not leaking from diaphragm, restore vehicle to original condition. Testing is complete.
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