MTD 700 Series Professional Shop Manual page 111

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4. When the following conditions are met:
• Key to START
• Brake is on
• PTO off
The starter solenoid trigger terminal will receive power (orange wire).
5. When the starter solenoid is triggered, it internally connects the heavy red cable from the battery with the
heavy red cable that leads to the starter motor. The starter spins.
Magneto
Primary winding
ground wire
Afterfire solenoid
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Magneto
Figure 7.19
Figure 7.20
Once the starter motor spins, we still need spark and fuel
to make the engine run. Looking at the circuits that do that:
1. The ignition sparks are generated by a magneto. The
magneto will work as long as the primary windings
are not grounded. With the key switch in any position
other than off, there is no connection between the M
(Magneto) terminal and the G (Ground) terminal.
See Figure 7.19.
2. There is an afterfire solenoid on the carburetor. When
it is energized, fuel flows normally through the carbu-
retor. When it is not energized, it closes off the fuel
flow through the main jet of the carburetor. The pur-
pose of the solenoid is to prevent unburned fuel from
being pumped through the engine after the ignition is
turned off. This unburned fuel accumulates in the
muffler and may ignite with an alarming noise.
See Figure 7.20.
3. The the key switch sends power to:
• The afterfire solenoid
• The OCR module "A1 pwr" terminal (if equipped)
Electrical
105