TSB : Fuel Injector: Testing and Inspection

Details

NOTE: Before opening any fuel system connection, always relieve fuel system pressure. To relieve fuel system pressure, remove trunk floor panel and fuel tank cover, disconnect fuel pump electrical connector at the pump, then start and run engine until it dies. Re-connect fuel pump connector. WARNING: FIRE HAZARD! Do not smoke or create any sparks where odor of fuel vapor is present. ELECTRICAL CHECK 1. Perform diagnostic output checks for fuel injectors. See COMPUTERIZED ENGINE CONTROLS . All injectors should "click". If not, check resistance through suspect injectors. ^ Resistance should be 15 - 17 ohms. If resistance through any injector(s) is not within specified range, replace injector(s). If all injector resistances are within the specified range and one or more did not click during output check, refer to COMPUTERIZED ENGINE CONTROLS and see OUTPUT DEVICES AND SIGNALS under TESTING PROCEDURES . SPRAY PATTERN, VOLUME AND LEAK CHECKING 1. Relieve fuel system pressure. Fuel Rail Connection To Pressure Regulator: 2. Disconnect fuel supply hose from fuel rail and disconnect vacuum hose and fuel hose to pressure regulator at fuel rail and regulator. Removing Pressure Regulator: 3. Remove pressure regulator from intake manifold, leaving bracket and fuel return line attached. 4. Remove fuel rail from intake manifold with injectors attached. Checking Fuel Injectors (Volume And Spray Pattern): 5. Route and reconnect hoses so that the fuel rail and injectors can be placed in measuring apparatus as shown in illustration. Fuel Pump Relay Socket Terminal ID: 6. Remove fuel pump relay and connect jumper wire between relay panel terminals #48 and #52 (turns fuel pump "ON"). 7. One at a time, energize injectors for 30 seconds by applying battery power and ground to injector electrical terminals. Observe the spray pattern while injectors are operating. ^ A fine cone shaped mist of fuel should spray from injectors. Injectors that release fuel in a stream or droplets should be cleaned or replaced. WARNING: Fire hazard! Use remote switch or long jumper wires so as not to create any sparks near the injector being tested. The mist of fuel can ignite very easily. 8. Check the quantity of fuel in each measuring container after 30 seconds of injector operation. ^ Should be 5.1oz - 5.8oz (150ml - 170ml). Clean or replace injectors that are not within specification. NOTE: If the fuel quantity for all injectors is the same but not within the specified range, check fuel filter , system pressure and fuel pump operation. 9. Wipe off tips of injectors and check for leaks. ^ some wetting is normal and one or two drops per minute with the fuel pump running is acceptable. Any more than two drops per minute indicates a leaking injector. NOTE: Leaking injectors and injectors with poor spray patterns can sometimes be cleaned with a chemical fuel system cleaner and re-used. Use a cleaner designed for fuel injectors. Also some gasoline brands contain cleaning additives for fuel injection systems. If clogged or leaking injectors are suspected, switching to one of these gasoline brands may help. If cleaning does not restore normal injector operation, replace the injector(s).