Fuel Injector: Testing and Inspection
***UPDATED BY TSB #F00193, JANUARY 11, 1993POWER SUPPLY CHECK
1. Disconnect injector harness electrical connector and turn ignition "ON".
2. Check for voltage at the W/R wire terminal of the harness side connector.
IGNITION "OFF:" 0V
IGNITION "ON:" 12V (battery voltage)
^ If no voltage is present, check main relay and wiring between main relay and injector harness connector.
RESISTANCE CHECK (OFF VEHICLE)
Individual Injector - Resistance Checking:
^ Check resistance between terminals on individual injectors.
RESISTANCE: 12 - 16 Ohms
^ If resistance is not within the specified range, replace injector(s).
INJECTOR SPRAY PATTERN AND LEAKAGE CHECKING
NOTE: Before performing fuel system work, relieve system pressure by starting engine with fuel pump relay (circuit open relay) disconnected and let run until engine dies. Carefully remove hose on outlet side of fuel filter. To avoid spraying fuel, cover with a clean rag while removing hose.
1. Remove intake manifold dynamic chamber and fuel rail with injectors. Leave fuel lines connected.
Fuel Rail (Delivery Pipe) W/Injectors Attached For Testing:
2. Secure injectors to fuel rail with wire, making certain that injectors are straight and cannot move.
Energizing Fuel Pump At Diagnostic Connector:
3. Energize fuel pump by bridging terminals "Fp" and "GND" of diagnostic test connector and turning the ignition "ON".
4. One at a time, place nozzle end of each injector into a suitable container, and energize injector momentarily by applying power and ground while observing spray pattern. A finely atomized, cone shaped mist of fuel should spray from injector nozzle.
WARNING: Fire hazard. Use appropriate connectors and long jumper wires. Do not create sparks near injectors or container of fuel. Injector fuel mist is easily ignited.
5. Repeat step 4 for each injector.
6. Dry injector tips with a clean cloth and check for fuel dripping. After a minute or so, some wetting or even a drop of fuel seeping from an injector nozzle is acceptable. More than one drip per minute, with the fuel pump running, is unacceptable.
6. 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.
NOTE: Some brands of gasoline contain a cleaning additive for fuel injection systems. If clogged or leaking injectors are suspected, switching to one of these brands may help.
7. If cleaning does not restore normal injector operation, replace injector(s).