COVER 3739123 - Caterpillar

Family Of Diesel EnginesFlushing of the complete fuel system is recommended whenever any fuel system component is removed. Due to small fuel injector clearances, any debris or air borne dust can cause injector seizures that may lead to other engine damage.
Whenever removing a fuel transfer pump, fuel line, fuel injector, or even a cylinder head, it is recommended that the fuel system ports be "capped" to prevent any debris from entering the fuel line. It is recommended that before restarting the engine, the complete fuel system should be flushed to help eliminate the small particles which impede fuel flow.
The most effective method to flush the fuel system is to remove the return line just ahead of the pressure valve and use a priming pump to force fuel through the fuel lines, heads, injectors, and filter. This should remove any debris. The amount of fuel required will depend on the size of the engine. For heavy fuel (residual) engines, flush with distillate fuel prior to removing fuel system components.