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, if necessary. Then prime the fuel system until clean fuel reaches the fuel injection line nuts. 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 linkage 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 probable location of a defective valve, and a new one should be installed in that cylinder to definitely determine if the valve removed was defective.
Never wire brush or scrape a fuel injection valve nozzle assembly as this will damage the finely machined orifice. Your AVSpare dealer has the proper tools for cleaning and testing fuel injection valves.
LOOSENING FUEL INJECTION VALVE NUT TO TEST VALVE
Removing Fuel Injection Valves: Clean around the edge of the camshaft and valve mechanism cover to prevent dirt from entering the valve mechanism when the cover is removed.
On tractors equipped with direct electric starting systems, the glow plug should first be removed eliminating the possibility of damaging the glow plug when removing a fuel injection valve. If equipped with glow plugs, see the topic, GLOW PLUGS.
- 1. Remove the cover.
REMOVING FUEL INJECTION VALVE
1-Retainer nut. 2-Cap. 3-Fuel injection valve body. 4-Fuel injection valve nozzle assembly. 5-Cap on the adapter through cover base.
- 2. Remove the fuel line between the injection valve and the adapter in the camshaft cover base. Install a plug in each end of this line and a cap (5) on the adapter to prevent dirt from entering the lines.
- 3. Remove the retainer nut (1).
- 4. Lift out the fuel injection valve body (3) and the fuel injection valve nozzle assembly (4) as a unit.
If the fuel injection valve will not be immediately installed, the cap (2) should be put on the valve body to prevent dirt entering the valve assembly.
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 (3) into the fuel injection valve nozzle assembly (4) 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 precombustion chamber opening. Turning the body in a clockwise direction and at the same time pressing down will assure alignment of the serrations.
- 3. Tighten the retainer nut to prevent leaks between the nozzle assembly and the nozzle assembly seats. A torque of 100 to 110 pounds feet is adequate to tighten the retainer nuts.
- 4. Reinstall the fuel injection line and tighten the nuts.
Fuel Injection Pumps
Testing Fuel Injection Pumps: It is not usual for one pump on an engine to require replacement unless all the pumps are worn. Worn fuel injection pumps will result in loss of power and hard starting. When loss of power and hard starting is accompanied with a clear exhaust, good compression and no blow-by gases from the crankcase breather, it indicates fuel injection pumps may be worn. The tools and information required to service and check fuel injection pumps are available at your AVSpare dealer.