Using Stethoscope

Using a stethoscope, check the injectors for a clicking sound at idle. Check that the sound is produced at shorter intervals as the engine speed increases.
CAUTION: Ensure that the sound from an adjacent injector is not being transmitted along the delivery pipe to an inoperative injector.

Fig 1: Illustrating Injection Operation Sound Check
Courtesy of KIA MOTORS AMERICA, INC.
If a stethoscope is not available, check the injector operation with your finger. If no vibration is felt, check the wiring connector, injector or injection signal from the ECU.

Fig 2: Illustrating Injection Operation Feel Check

Courtesy of KIA MOTORS AMERICA, INC.