INSERT 3483751 - Caterpillar

When improper fuel injection is affecting the diesel engine operation, a systematic check should be made to determine the cause. The most likely cause is dirt or water in the fuel. Drain the sediment from the diesel fuel tank and drain the fuel filter housing. Check the fuel pressure gauge as mentioned in the topic, FUEL SYSTEM. Replace the filter elements, and clean the primary fuel filter if necessary. Then prime the fuel system until clean fuel passes through the fuel vent drain tube. If the fuel system is air bound, priming the system will overcome the difficulty.When the engine is running irregularly, and smoking, a fuel injection valve may not be spraying the fuel properly.As the clearance between the plunger and the barrel of a fuel injection pump increases, due to wear, fuel leakage occurs. When the leakage increases to the point where insufficient fuel is injected into the cylinder, a loss of power is noticeable. With the loss of power, hard starting is also encountered.Fuel Injection Valves
Testing Fuel Injection Valves: Whenever an engine performs in such a manner that a fuel injection valve is suspected of causing trouble, test all fuel injection valves. To test the injection valves, loosen the fuel injection line nuts at the fuel injection pumps, one at a time, while the engine is running. When a nut is loosened and the exhaust smoking is completely or partially eliminated and the irregularity in running is not affected, this identifies the defective valve and a new one should be installed in that cylinder. These valves can be tested by your Caterpillar dealer.
LOOSEN FUEL INJECTION LINE NUT TO TEST VALVE
REMOVING FUEL INJECTION VALVE
1-Retainer nut. 2-Fuel injection valve nozzle assembly. 3-Plug. 4-Cover. Removing Fuel Injection Valves: Before removing a valve clean the dirt from around the valve and connections. If the engine is equipped with glow plug starting aids, the glow plug should first be removed before removing and replacing a fuel injection valve to eliminate the possibility of damaging the glow plug. See the topic GLOW PLUGS.Disconnect the fuel injection line from the injection valve and pump. Install the plug (3) and cover (4). Remove the valve retainer nut (1) and lift out the nozzle assembly (2) and body as a unit. Installing Fuel Injection Valves: Before installation of a fuel injection valve, be sure the wrench is clean. Put the dust cover on the valve body as soon as possible to prevent dirt entering the fuel passage. Install the fuel injection valve in the following manner:1. Screw the valve body 7 into the fuel injection valve nozzle assembly only finger tight. The threads of the body and nozzle assembly are made to fit loosely. The clearance between the threads provides a passage for fuel to enter the nozzle assembly from the body.2. Insert the nozzle assembly and valve body as a unit into the pre-combustion chamber opening. Turning the body in a clockwise direction and at the same time pressing down will assure