JUNCTION BLOCK 7L3220 - Caterpillar

Illustration 1 g00598910
(1) Fuel injection rack (2) Fuel-on direction
Use a screwdriver to move each fuel injection rack (1) to the fuel-on position. If an injector is delivering less than the correct amount of fuel, the cylinder will misfire. Moving the fuel injection rack to the fuel-on position will lessen the misfire. This may also eliminate the misfire. If an injector is delivering more than the correct amount of fuel, moving the fuel injection rack to the fuel-on position will increase an existing engine knock. Stop this test if the misfire or the engine knock can not be attributed to a specific cylinder.
If a misfire or engine knock can be isolated to a single cylinder, check the injection timing and the synchronization of the suspect cylinder. Make adjustments, if necessary. If adjustment does not resolve the problem, replace the injector. Ream the injector sleeve if the seat area for the injector is pitted. Replace the injector sleeve, if necessary. Refer to Troubleshooting, "Unit Injector". Verify synchronization and timing after replacing an injector.