Fuel System Pressure Leak Down Test
- Connect a 0-60 psi (0-4.2 kg/cm2 ) fuel pressure gauge to the pressure test port on fuel rail. Start engine, bring to operating temperature and measure fuel system pressure. Shut engine off. Wait 30 minutes and check fuel pressure. Fuel pressure should be within 20 psi (1.4 kg/cm2 ) of first reading. If pressure is not as specified, go to next step.
- Relieve fuel system pressure. See FUEL SYSTEM PRESSURE RELEASE under FUEL PRESSURE . Connect 3/8" Fuel Line Pressure Test Adapter (6631) between fuel supply line and fuel rail. Connect 5/16" Fuel Line Pressure Test Adapter (6539) between fuel return line and fuel rail. Start engine and measure fuel system pressure.
- Shut engine off. Clamp off 5/16" rubber hose of adapter between fuel return line and adapter. Wait 30 minutes and check fuel pressure. Fuel pressure should be within 20 psi (1.4 kg/cm2 ) of first reading. If pressure is as specified, go to next step. If pressure is not as specified, leak is in fuel pump tank module. Replace fuel pump tank module.
- Remove clamp from 5/16" rubber hose. Start engine and measure fuel system pressure. Shut engine off. Clamp off 3/8" rubber hose of adapter between fuel supply line and fuel rail. Wait 30 minutes and check fuel pressure. If pressure drops more than 20 psi (1.4 kg/cm2 ) in 30 minutes, pressure is bleeding past fuel pressure regulator located on fuel rail. Replace fuel pressure regulator.