Fuel Injector Balance Test

Diagnostic Chart:

Description:

1. First Reading 2. Second Reading:

CIRCUIT DESCRIPTION

The Fuel Injector Tester J 39021, the Injector Switch Box J 39021-210 and the Injector Harness Connector J 39021-303 energize the injector for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector. All injectors should be within the same pressure drop range the average pressure drop value for all injectors is ±10 kPa (1.5 psi).

TEST DESCRIPTION

CAUTION: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal Injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gauge. Place the towel in an approved container when the connection of the fuel pressure gauge is complete.

4. The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to Hot Soak fuel boiling.

5. The fuel pressure should be within the specified range. If the fuel pressure is not within the specified range, go to Fuel System Diagnosis. System Diagnosis - Fuel System

6. Allow the fuel pressure to stabilize about 3 minutes. On a hot vehicle fuel pressure may increase due to fuel expansion after the pump stops running. This is a normal condition but the fuel pressure should stabilize and hold. The fuel pressure should reach a steady value. If the fuel pressure does not reach a steady value, refer to Fuel System Diagnosis. System Diagnosis - Fuel System

7. If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading. Refer to the illustration above.