The injector is used to spray fuel under high pressure. Before checking the fuel injectors, first inspect the following:
- fuel filter, it may already be clogged to the brim and needs to be replaced;
- spark plugs that have a service life;
- loss of compression when the compression rings have long since exhausted their service life;
- or the timing marks may be knocked off, but this is a rare case.
Electromagnetic fuel injectors contain a solenoid that receives a pulse from the ECU. To test the injectors, first disconnect the fuel connector leading to the injector and connect the wires directly to the battery, observing polarity. Turn on the ignition to allow the fuel pump to deliver fuel to the fuel rail. If the injector sprays fuel, it's working.
But there's another method that requires a fuel injector resistance tester. Search online for the specific vehicle and injector manufacturer, and determine their resistance; they come in both high- and low-resistance varieties. Turn off the ignition and disconnect the negative battery terminal.
Disconnect the connector leading to the fuel injector using a small screwdriver, turn the device into resistance test mode, and connect the contacts to the injectors.
The resistance in the fuel injector solenoid should be from 11-12 ohms to 15-17 ohms, if the injectors have low resistance, then from 2 to 5 ohms.
If the reading is higher or lower than the acceptable value, the injector must be removed or replaced. After this procedure, connect the negative battery terminal, connect the connector to the fuel injector, and start the engine.
If the car engine runs unsteadily, then the faulty injector has been identified; if not, then you need to continue the same process with other injectors.
Checking the electrical power supply
A simple test is to touch the fuel injector; it should vibrate. If you don't feel it, the wiring or injector is faulty. You can also disconnect each injector one by one from the electrical connector and connect it directly to the battery. If vibration and spraying occur, the fuel injector is working properly.
Hearing test
Using a stethoscope, experienced technicians can listen to each injector for proper operation without disassembling it while the engine is running. A working injector can be identified by listening to it as follows: it should produce a steady clicking sound. A loud knocking sound indicates that the injector is clogged with fuel deposits and requires cleaning or replacement.