Lesson 2/Learning Event 3
When a vehicle uses too much fuel, the first thing to look for are LEAKS! If the driver says that the engine
develops full power but uses too much fuel, it's a good possibility that this is what is wrong. Much of the
fuel system is on the right side of the vehicle, and the hot exhaust system is there also. So, you can see the
While you are looking for leaks, make sure all fuel line fittings are tight. If no leaks are found, turn on the
in-tank pump and recheck for leaks. Start the engine and check for leaks.
Check the air intake system for a blockage, such as a clogged air cleaner. (Remember, a restricted air intake
system generally causes black exhaust and low power.)
The engine will also use too much fuel if the injector pump is out of time or is improperly adjusted.
Generally, when the engine is out of adjustment, it will also be low on power. If this seems to be the
trouble, notify your support maintenance unit.
The manifold flame heater aids in starting the multifuel engine when it is cold. If you have trouble starting
the engine even with the manifold heater, it is possible the heater is not working properly. You can
troubleshoot the heater in the following manner:
Inspect the entire intake manifold flame heater assembly. Make sure it is all there and is connected properly.
If the fuel lines, wiring, and ignition unit look all right, find out which system is at fault. It might be the
fuel system or the ignition system.
First, make sure there are no leaks when the intake manifold flame heater switch is closed. Next, disconnect
the high-tension lead at the spark plug. Hold the wire about 1/4 inch from the metal part of the spark plug
and have someone turn on the intake manifold heater switch. If electrical sparks continue to jump the gap
between the wire and the plug metal, the electrical system is all right. If no spark jumps, check out the rest
of the electrical circuit.
If the electrical system is all right, check out the fuel system up to the fuel pump. Make sure the lines are
not clogged. If the trouble lies in the fuel pump or nozzle, notify your support maintenance unit.