A-7 ~ Fuel Injector Balance Test

CAUTION: In order to reduce the risk of fire and personal injury, wrap a shop towel around the fuel pressure connection. The towel will absorb any fuel leakage that occurs when installing the fuel pressure gauge. Place the towel in an approved container when the installation of the fuel pressure gauge is complete.

Fuel Pressure Drop Testing With Fuel Injector Tester (J 39201):

Circuit Description
The Fuel Injector Tester (J 39201) is used to energize the injector for a precise amount of time, thus spraying a measured amount of fuel into the manifold. This causes a drop in fuel rail pressure that can be recorded and used to compare each injector. All injectors should have the same pressure drop ± 10 kPa (1.5 psi).

Table A-7 - Fuel Injector Balance Test (1 Of 2):

Table A-7 - Fuel Injector Balance Test (2 Of 2):

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
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, proceed with fuel system diagnosis.
6. The fuel pressure should reach a steady value.
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.