Fuel System Pressure Test
- Remove cap from pressure fitting in fuel rail. See Fig 1 . Using a shop towel to absorb any spilled fuel, connect a 0-100 psi (0-7.0 kg/cm2 ) fuel pressure gauge to pressure fitting on fuel rail. Disconnect vacuum hose from fuel pressure regulator. Start engine.
- Pressure should be approximately 39 psi (2.74 kg/cm2 ) with vacuum hose disconnected and 31 psi (2.18 kg/cm2 ) with vacuum hose connected to fuel pressure regulator.
- If fuel pressure is not 8-10 psi (.56-.70 kg/cm2 ) higher with vacuum hose disconnected from fuel pressure regulator, inspect vacuum hose for blockage, leaks, kinks or other damage. If vacuum hose is okay, replace fuel pressure regulator.
- If fuel pressure exceeds 45 psi (3.2 kg/cm2
), check fuel return line for kinks or blockage. If fuel pressure is low, release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE PROCEDURE above. Disconnect fuel return line on fuel rail near fuel pressure regulator. Connect 5/16" fuel hose between disconnected fuel return line and fuel rail.CAUTION: Fuel pressure will rise as high as 100 psi (7.0 kg/cm2 ) when fuel return line is pinched off. Ensure connections are properly secured. DO NOT pinch off hose for longer than 5 seconds.
- Restart vehicle and let engine idle. Momentarily pinch off hose connected to fuel return line. Note fuel gauge pressure reading. Pressure should rise to approximately 75 psi (5.3 kg/cm2 ) within 2 seconds.
- If fuel pressure rises as specified, pressure is operating at maximum capacity and is correct. If fuel pressure does not rise as specified, turn engine off. Release fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE PROCEDURE above. Raise and support vehicle. Disconnect fuel supply line at inlet (fuel tank side) of fuel filter. Connect 3/8" fuel hose between fuel filter and fuel supply line.
- Restart vehicle and let engine idle. Momentarily pinch off hose connected to fuel supply line. Note fuel pressure gauge reading. Pressure should rise to approximately 75 psi (5.3 kg/cm2 ) within 2 seconds. If fuel pressure rises as specified, but pressure is not same at fuel rail, check for plugged or restricted fuel filter. Also check fuel supply line between fuel filter and fuel rail for kinks or blockage.