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M48 Tank
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11.4. The fuel pressure at the injectors is held con-
stant by the fuel pressure regulator. The amount
of fuel delivered to the cylinders is controlled by
the length of time that the individual fuel injectors
are triggered. The length of time the injectors
are triggered varies from 1.5 to 8.0 milliseconds.
11.5. Both injectors are triggered simultaneously.
Each triggering causes the injector to spray half
the amount of fuel required by the corresponding
cylinder on the next cycle.
11.6. The injectors are “hot” as long as the key switch
is on. The injection is triggered by the comple-
tion of a ground path within the ECU.
11.7. The injectors make an audible “click” each time
they are triggered. If this click cannot be heard
or felt, there may be a problem with the injector
itself, or there may be a problem in the wiring
harness.
11.8. If a fuel injector is suspect, the circuit may be
tested with a commonly available “noid” light, or
the injector may be triggered using an electronic
fuel injection pulse timer (eg. Thexton model
number 139) in conjunction with a fuel pressure
gauge. With the key switch off, triggering the
injector should result in a measured drop in fuel
pressure.
Figure 11.7
11.9. The ignition coils are also controlled by the ECU.
Each cylinder has its own coil. See Figure 11.9.
11.10. The plastic-cased ECU is mounted to the frame,
above the fuel pump. See Figure 11.10.
11.11. The ECU is the brain of the engine control sys-
tem. It is very durable, but there are some rules
to follow in order to avoid damage to the ECU:
• If you diagnose a faulty ECU, do not replace it
without calling Cub cadet Technical Support for
specific handling instructions.
• Previously mentioned: do not use a conventional
test light to look for power in the engine control
circuit.
• Previously mentioned: do not disconnect any
electrical devices while the engine is running.
• Do not reverse the battery terminal connections.
Figure 11.9
Figure 11.10