Lesson 2/Learning Event 3
Trace the fuel feed, fuel return, and vent lines along the frame. Make sure they are not broken, leaking,
bent, crimped, or damaged in any way. Make sure the lines are clipped securely to the frame so that they
won't break from vibration or wear holes by rubbing against nearby parts.
As you trace the fuel line, you will come to the primary fuel filter which is mounted to a frame bracket
under the engine generator. Check the filter closely for insecure mounting, leaks, and damage. Open the
drain valve on the bottom of the filter and watch for any dirt or water. Always catch drained fuel in a
container and dispose of it properly so that you will not cause a fire hazard.
If any dirt or water is found in the primary filter, drain the secondary filter. If any is found in the secondary
filter, drain the final filter. Both the secondary and final fuel filters are mounted on the left rear of the
engine. When a large amount of dirt or water is found in the filters (especially the final filter), clean the
primary filter and replace the secondary and final fuel filter elements.
Inspect the fuel injection pump, operating linkage, and connecting lines for improper mounting, external
damage, and leaks. Since engine lubricating oil is used in the injector pump, you will have to be on the
lookout for oil leaks as well as fuel leaks while you inspect the injector pump. Also inspect the condition of
the protective dust caps at the high-pressure outlets of the injection pump hydraulic head. Use extreme
caution when checking for leaks or working near high-pressure fuel lines. The fuel is under enough pressure
to puncture your skin and could cause blood poisoning. Keep your hands away from suspected leaks while
the engine is running.
Inspect the high-pressure lines, fuel injector nozzles, and fuel return lines for damage, leaks, and improper
mounting. Use a wrench to check the fuel injector nozzle mounting bolts for looseness. Loose bolts should
be tightened with a torque wrench.
Move to the opposite side of the engine compartment and inspect the air induction system. Check the air
intake or rain hood for excess dirt, and check the air intake flexible tube for condition. Make sure that the
flexible tube does not leak. Check the air cleaner mounting bolts for tightness.