Lesson 2/Learning Event 3
Learning Event 3: DESCRIBE THE PROCEDURES FOR INSPECTION OF
COMPRESSION IGNITION ENGINE FUEL SYSTEMS
INTRODUCTION
You now know the many differences in construction and operation between the fuel systems of compression
ignition and spark ignition engines. There are also a lot of differences in the maintenance procedures
performed on the two systems. As a rule, maintaining the fuel systems of compression ignition engines
requires even more knowledge and skill than spark ignition systems. Mechanics who are capable and well
trained on this are in great demand, so it will be to your advantage to put forth extra effort on the subject.
It is true that most of the major maintenance on compression ignition fuel systems will be done by fuel and
electrical systems repairers, but there are many things to be done by an organizational repairer. For instance,
you, as a wheeled vehicle mechanic working at organization level, may be called upon to do any of the
following: inspect, test, service, clean, tighten, and make some adjustments or even replace some
components of the fuel and air induction systems.
The work done by you will be detecting and repairing troubles while they are small, before they have a
chance to cause serious problems. Indeed, this is the most important part of all maintenance!
INSPECTION OF COMPONENTS
You will probably do more work on multifuel systems than on diesel fuel systems, so the major part of this
lesson will deal with maintenance of air-fuel systems of the 2 1/2-ton trucks, M35A1 and M35A2, which are
powered by multifuel engines. The following is how you should go about the job of inspecting the air-fuel
systems of these trucks:
Start by inspecting the fuel tank for holes, rusty spots, and improper mounting. If the tank has a rusty spot
or if some other part is rubbing against the tank, a leak will soon develop. Inspect the filler cap to make sure
it seals the filler neck and that it is held by its retaining chain. Check the condition of the filler neck and
the fuel strainer. Make a visual check of the fuel gage sending unit and fuel pump electrical connections.
Check for any damaged or leaking fittings and connections.
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