Fuel Injector Balance Test

Diagnostic Chart (Part 1 Of 3):

Diagnostic Chart (Part 2 Of 3):

Diagnostic Chart (Part 3 Of 3):

Injector Balance Test Example:

INJECTOR BALANCE TEST EXAMPLE

Test Results: Combine all of the injector pressure drops and divide this number by the amount of injectors available. This is the average pressure drop. Each individual injectors pressure drop value must be within 10 kPa (1.5 psi) of the average pressure drop value.

CIRCUIT DESCRIPTION
The scan tool first energizes the fuel pump and then the injectors 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.

TEST DESCRIPTION

CAUTION: Refer to Shop Towel Fuel Leak Caution in Service Precautions.

3. The engine coolant temperature must be less than the operating temperature in order to avoid irregular fuel pressure readings caused by hot soak fuel boiling.
4. When the fuel pump is running, the fuel pressure should be within the specified range.
5. Allow the fuel pressure to stabilize for approximately 3 minutes. On a hot vehicle, the fuel pressure may increase because of fuel expansion after the pump stops running. This is a normal condition, but the fuel pressure should stabilize and reach a steady value.
6. 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.