TOOL GP 3990774 - Caterpillar

Recommended Procedure1. Fuel Return Manifold Leaks and/or Leaks at Fuel Return Boots or Connectors Remove the valve cover(s). Make a visual inspection of the fuel return manifold, fuel return boots, and connectors. Boots and/or connectors with damage or wrongly installed will let fuel get into the oil. If you do not see leaks during the visual inspection, start the engine and visually inspect while the engine is running. Boots and/or connectors can cause leakage if the fuel return line has a restriction.2. Loose Fuel Injection Nozzle Nut(s) A loose fuel injection nozzle nut can cause fuel leakage. Tighten nozzle nut(s) to 30 5 lb. ft. (4,1 0,7 mkg).3. Bad Fuel Nozzle(s) Check fuel nozzle(s) for cracks in inlet fitting, inlet line, or nozzle body. If you do not see a crack, start the engine and visually inspect each nozzle for leaks. Cracks in the inlet fitting and nozzle body are nozzle defects. Cracks in the inlet line are caused by the nozzle not being tightened correctly.4. Bad Diaphragm in Fuel Transfer Pump A bad diaphragm will cause fuel leakage through the "orifice" (small hole) in the fuel transfer pump housing. If you do not see leakage, make sure the orifice is open. Start the engine and again look for possible leakage. If the pump has leaks, install a new pump.5. Loose Fuel Injection Pump Retaining Bushing Loose retaining bushings will not hold the barrel of the injection pump correctly against the seat in the pump housing and fuel can get into the crankcase. A loose bushing can cause the engine to "misfire" (ignition not regular). A loose bushing can cause fuel leakage to the outside of the pump housing. Remove the fuel lines at the fuel injection pump and tighten each retaining bushing to 100 10 lb. ft. (13,8 1,4 mkg). Note: To tighten the three rear retaining bushings the pump housing must be removed from the engine.6. Fuel Leaks Between Injection Pump Barrel(s) and Injection Pump Housing Dirt or foreign material under the barrel of the fuel injection pump will cause fuel leakage into the crankcase. Remove the housing of the fuel injection pump and the governor from the engine. Remove the plunger and barrel assemblies from the pump housing. Inspect the seat area of the barrel and housing. Be sure the seat is smooth and flat. Check the timing dimension and adjust as necessary. Install the fuel injection pumps.7. Badly Worn Fuel Injection Pumps It is possible for one or more of the plunger and barrel assemblies to be worn enough to cause fuel leakage between the plunger and barrel. Remove the housing of the fuel injection pump and the governor from the engine. Test the fuel injection pump on the test bench for fuel injection pumps. If a test bench is not available, install new plunger and barrel assemblies in place of those with damage.