Test Description

The numbers below refer to step numbers in diagnostic procedure.

1. 3
   
   Engine Coolant Temperature (ECT) must be below operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
2. 6
   
   If pressure drop value for each fuel injector is within 1.5 psi (10 kPa) of average pressure drop value, fuel injectors are flowing properly. Calculate pressure drop value for each fuel injector by subtracting second pressure reading from first pressure reading. See Fig 1.

Fig 1: Injector Balance Test Example (2.2L Sonoma & S10 Pickup)

Courtesy of GENERAL MOTORS CORP.