Fuel Injector Balance Test With Special Tool

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Fuel Injector Balance Test With Special Tool:

Injector Balance Test Example:

CIRCUIT DESCRIPTION
The J 39021 Fuel Injector Tester is used to energize the fuel injector for a precise time period 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.

DIAGNOSTIC AIDS
Any fuel injector that varies significantly (more than 10 kPa) requires service.

TEST DESCRIPTION

CAUTION: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of tire 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 Pressure Test. Fuel System Pressure Test
6. The fuel pressure should reach a steady value. If the fuel pressure does not reach a steady value, go to Fuel System Pressure Test.
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. Go to the Injector Balance Test Example.