Pressure Testing (Fuel Injection)
- Disconnect negative battery cable. Relieve fuel pressure. See RELIEVING FUEL PRESSURE (FUEL INJECTION) . Connect Fuel Pressure Gauge (07406-0040001 ) at 6-mm bolt. Reconnect negative battery cable. Start engine and note fuel pressure. If vehicle will not start, check for spark. If it has spark and no fuel pressure is evident, inspect fuel pump main relay.
- Remove connector from fuel pump main relay. See Fig 1 . With a test light, check for battery voltage on Black/Yellow wire at fuel pump relay connector. If battery voltage is present, jumper Black/Yellow (positive) and Yellow (ground). If fuel pump runs, proceed to step 3). If fuel pump fails to run, see SYSTEM/COMPONENT TESTS - EFI article. If no voltage is present on the Black/Yellow wire, check for open in wire between fuel pump main relay connector and No. 2 fuse on fuse box. Proceed to step 3) after repairing circuit.
- Disconnect vacuum hose from pressure regulator and check for manifold vacuum. If vacuum is not present, check for restriction in vacuum port or hose. Plug vacuum hose and inspect fuel pressure gauge reading. Gauge reading should be 36-41 psi (2.6-2.9 kg/cm2 ). Pressure should rise slightly when vacuum hose is disconnected.
- If pressure is higher than specified, inspect for pinched or clogged fuel return line between fuel rail and fuel tank. If no problem is found in fuel line, replace pressure regulator.
- If pressure is lower than specified, inspect for plugged fuel filter. If filter is not plugged, lightly pinch fuel return line. If fuel pressure does not rise, replace fuel pump. If fuel pressure does rise, replace pressure regulator.NOTE: If vehicle starts and runs, fuel pump main relay is okay.