VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. Inspect air induction system for possible vacuum leaks.
FUEL PUMP AMPERAGE TEST
Note. Perform FUEL PUMP AMPERAGE TEST in conjunction with FUEL PUMP CAPACITY TEST, FUEL PUMP PRESSURE TEST and FUEL PRESSURE LEAKDOWN TEST.
Scheme 1
Scheme 2
Scheme 3
Scheme 4
- Ensure fuel tank temperature is more than 50°F (10°C). Connect DRB Low Current Shunt (LCS) adapter into DRB-III scan tool SET 1 connector. (Scheme 1) Connect DRB-III scan tool to Data Link Connector (DLC). Connect test lead cables into 10-amp (10A +) and common (-) connectors on LCS. Access MAIN MENU on scan tool. Press DVOM button.
- Use left/right arrow keys to highlight CHANNEL 1 function on scan tool. Press ENTER 3 times. Use up/down arrow keys to high light RANGE on scan tool. Press ENTER to change from 2-amp scale to 10-amp scale. Remove Power Distribution Center (PDC) cover and remove fuel pump relay. Depending on make or model of vehicle, 3 different relays are used. Use the following procedure for appropriate relay: Type 1 Fuel Pump Relay Attach test leads from LCS adapter into PDC relay cavities No. 30 and 87. (Scheme 2) Type 2 Fuel Pump Relay Attach test leads from LCS adapter into PDC relay cavities No. 30 and 87. (Scheme 3) Type 3 Fuel Pump Relay Attach test leads from LCS adapter into PDC relay cavities No. 3 and 5. (Scheme 4) Fuel pump will be operated when LCS adapter leads are connected to relay cavities. Read fuel pump amperage from DRB scan tool screen. Amperage should be less than 10 amps. If amperage is 10 amps or more, replace fuel pump module assembly. If amperage is less than 10 amps and FUEL PUMP PRESSURE, FUEL PUMP CAPACITY and FUEL PRESSURE LEAK DOWN test readings are okay, fuel pump module is okay.
FUEL PUMP PRESSURE TEST
Note. For additional information on fuel pressure and fuel pump testing procedures, see appropriate NO TROUBLE CODE (NTC) TEST and NO START (NS) TEST in appropriate SELF-DIAGNOSTICS article.
FUEL PRESSURE LEAKDOWN TEST
Note. Perform FUEL PRESSURE LEAKDOWN TEST in conjunction with FUEL PUMP CAPACITY TEST and FUEL PUMP PRESSURE TEST. See FUEL PUMP CAPACITY TEST and FUEL PUMP PRESSURE TEST .
- Release fuel system pressure. See «FUEL PRESSURE RELEASE»(ref-9164-S33206637422000100900000) . Remove air cleaner housing (if necessary) to access quick-connect fuel fittings. Disconnect fuel supply line quick-connect fittings at fuel rail. Connect Fuel Line Pressure Test Adapter (6539 ) for 5/16" fuel lines, or Fuel Line Pressure Test Adapter (6631 ) for 3/8" fuel lines, to the disconnected fuel supply line.
- Connect 0-60 psi fuel pressure test gauge to test port on appropriate Fuel Line Pressure Test Adapter. Start engine and bring to normal operating temperature. Observe fuel pressure test gauge. Fuel system pressure should be 44-54 psi (3.1-3.8 kg/cm 2 ). Shut engine off. Fuel system pressure should not fall below 30 psi (2.1 kg/cm 2 ) for 5 minutes. Go to next step.
- If fuel system pressure falls below 30 psi (2.1 kg/cm 2 ), check fuel injector, check valve inside fuel pump module or fuel tube/line for leaks. To diagnose components and pinpoint fuel system leaks, perform the following tests: Fuel Injector Or Fuel Rail Leakage Start engine and operate at idle for 2 minutes. Shut off engine. Clamp off rubber hose portion of Fuel Line Pressure Test Adapter between fuel rail and test port "Tee" on Fuel Line Pressure Test Adapter. If fuel system pressure does not fall below 30 psi (2.1 kg/cm 2 ) for 5 minutes, fuel injector or fuel rail is leaking. Repair as necessary. Fuel Pump Check Valve, Filter/Regulator Check Valve Or Fuel Tube/Line Leakage Start engine and operate at idle for 2 minutes. Shut off engine. Clamp off rubber hose portion of Fuel Line Pressure Test Adapter between vehicle fuel line and test port "Tee" on Fuel Line Pressure Test Adapter. If fuel system pressure does not fall below 30 psi (2.1 kg/cm 2 ) for 5 minutes, fuel rail and fuel injectors are not leaking. Check fuel lines and tubes for leakage. If fuel lines and tubes are okay, check electric fuel pump or filter/regulator check valves for leakage. A quick loss of fuel system pressure usually indicates defective check valve in the filter/regulator. A slow loss of pressure usually indicates a defective check valve in the electric fuel pump. Repair as necessary.