FA627396 Force DECAL-STBD

Fuel System
Difficulty within the fuel system can be classed in one of two groups: lack of fuel or too much fuel for proper combustion.Many times the fuel system is blamed when the fault lies elsewhere, especially when smoky exhaust is the problem. Smoky exhaust can be the result of a faulty fuel injection valve, but it can also be caused by lack of air for complete combustion, overloading at high altitude, excessive oil burning or lack of compression.Visual Inspection
1. Observe the fuel pressure gauge reading. Lack of pressure indicates difficulty in the supply side of the system.2. Check the fuel level in the supply tank and the fuel tank cap vent for being plugged.3. See that the vent valve is closed.4. Check for leakage in the fuel supply lines and components or for a kinked or restricted supply line.5. Replace the fuel filter element and clean the primary fuel filter if so equipped.6. Inspect the fuel bypass valve to see that it moves freely and that dirt is not holding the plunger off its seat. Be certain the spring has correct tension.7. Bleed the fuel system to remove trapped air.Testing Fuel Injection Equipment
A simple check can be made to determine which cylinder is misfiring or causes puffing black smoke. With the engine running at a speed which makes the defect most pronounced, momentarily loosen the fuel line nut on an injection pump sufficiently to "cut out" the cylinder. Check each cylinder in the same manner. If one is found where loosening makes no difference in the irregular operation or causes puffing black smoke to cease, the pump and valve for only that cylinder need be tested.Checking Fuel Injection Valve
Examine fuel injection valves for:1. Excessive carbon on tip of nozzle or in orifice.2. Erosion of the orifice.3. Screen plugged with dirt.The condition of a capsule-type nozzle assembly can be tested on the Caterpillar Diesel Fuel Injection Test Bench, and the rate of leakage of the nozzle assembly can be determined.Checking Fuel Injection Pump Lifter Washer and Pump Plunger
The timing dimension should be checked and adjusted, if necessary, by setting the fuel injection pump timing dimension with the fuel injection pump off the engine. This will assure that the point of the fuel injection is correct. If the timing dimension is too small, injection will begin early, and if too great, injection will be late.When pump plunger wear becomes excessive, the lifter washer may also be worn so it will not make full contact with the end of a new plunger. To avoid rapid wear on the end of the new plunger, replace the lifters having washers showing visible wear.
WEAR BETWEEN LIFTER WASHER AND PLUNGER
Fig. A illustrates the contact surfaces of a new pump plunger and a new lifter washer. In Fig. B the pump plunger and lifter washer have worn considerably. Fig. C shows how the flat end of a new plunger makes poor contact with a worn lifter washer, resulting in rapid wear to both parts.A pump can maintain a satisfactory discharge rate and yet be unserviceable because of delayed timing resulting from wear on the lower end of the plunger. When testing a pump which has been in use for a long time, check the plunger length with a micrometer. Discard the pump if the plunger measures less than the minimum length (worn) dimension. Inspect the upper diameter of the plunger for wear. Performance of pumps worn in this manner can be checked as described in the Instructions for Fuel Injection Test Bench.Fuel Injection Service
Fuel Injection Valve
When installing a fuel injection valve, always check the seats of both the nozzle and the precombustion chamber. The nozzle assembly should be only finger-tight on the body. It is important to maintain the nozzle retaining nut torque to 105 5 lb. ft. (14.5 0.7 mkg). EXCESSIVE TORQUE will damage the nozzle. LESS TORQUE will allow the nozzle to leak and may cause the nozzle case to bulge or split.Fuel Injection Pump
Use an 8S4613 Wrench and 8S2244 Extractor to remove and install fuel injection pumps.When removing fuel injection pumps, spacers and lifters the components should be kept together and marked so they can be installed in their respective locations.While disassembling fuel injection pumps, exercise considerable care to prevent damage to the plunger surfaces. The barrel and the plunger are matched and are not interchangeable. Use extreme care when inserting the plunger into the bore of the barrel.Fuel Injection Pump Installation
The installation of fuel injection pumps requires that the lifter be at a low point and the fuel rack be centered or at "zero" position. To center or "zero" the rack, install the 7S7113 Rack Setting Gauge and set it at .000 in., retract the speed limiter, and move the rack in "fuel on" direction until it contacts the gauge. To install the pump, sight down the pump and align notches in bonnet and barrel with slot in the pump gear segment. Slot is 180° from pump gear segment center tooth.
RACK SETTING GAUGE INSTALLED
1. 7S7113 Rack Setting Gauge. A. 9S240 Rack Positioning Tool Group can also be used.Position the notches in bonnet and barrel to align with dowels in the housing. Install the pump. Keep a downward force (by hand) on the pump and install the bushing finger tight, until flush with top of housing. If the bushing cannot be assembled this far finger tight, remove the bushing and pump. The threads, on the bushing or in the housing, can be the restriction. Align the pump components and reinstall it. If the bushing installs correctly, tighten it to a torque of 150 10 lb. ft. (20.7 1.4 mkg). Overtightening the bushing can damage the housing or if the bushing is not tight enough, the pump will leak.Total rack travel, approximately .800 in. (20.32 mm), will be reduced if the pump is installed one or more teeth off in either the "fuel on" or "fuel off" side of its gear segment. The only way to