Chart C-2A Injector Balance Test

Chart C-2A - Injector Balance Test:

CHART C-2A - INJECTOR BALANCE TEST

Circuit Description:

The injector balance tester is a tool used to turn the injector on 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 we can record and compare between each injector. All injectors should have the same amount of pressure drop (± 10 kpa). Any injector with a pressure drop that is 10 kpa (or more) greater or less than the average drop of the other injectors should be considered faulty and replaced.

STEP 1

Engine "cool down" period (10 minutes) is necessary to avoid irregular readings due to "Hot Soak" fuel boiling. With ignition "off" connect fuel gauge to fuel pressure tap. Wrap a shop towel around fitting while connecting gauge to avoid fuel spillage.

Disconnect harness connectors at all injectors, and connect injector tester to one injector. On Turbo equipped engines, use adaptor harness furnished with injector tester to energize injectors that are not accessible. Follow manufacturers instructions for use of adaptor harness. Ignition must be off at least 10 seconds to complete ECM shutdown cycle. Fuel pump should run about 2 seconds after ignition is turned on. At this point, insert clear tubing attached to vent valve into a suitable container and bleed air from gauge and hose to insure accurate gauge operation. Repeat this step until all air is bled from gauge.

STEP 2

Turn ignition "off" for 10 seconds and then "on" again to get fuel pressure to its maximum. Record this initial pressure reading. Energize tester one time and note pressure drop at its lowest point (Disregard any slight pressure increase after drop hits low point). By subtracting this second pressure reading from the initial pressure we have the actual amount of injector pressure drop.

STEP 3

Repeat step 2 on each injector and compare the amount of drop. Usually, good injectors will have virtually the same drop. Retest any injector that has apressure difference of 10 kPa, either more or less than the average of the other injectors on the engine. Replace any injector that also fails the retest. If thepressure drop of all injectors is within 10 kPa of this average, the injectors appear to be flowing properly.

NOTE: The entire test should not be repeated more than once without running the engine to prevent flooding. (This includes any retest on faulty injectors)