MTD 700 Series - Troubleshooting Common Issues

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TROUBLE SHOOTING CHART FOR ELECTRIC START MODELS
TROUBLE LOOK FOR
REMEDY
Engine will not
crank
Battery installed incor¬
rectly
The battery m jst be Installed wjth the negative, identified at the terminal post by (Neg, N or -),
grounded. Thu positive (Pos, P or -h) attaches to the large cable from the solenoid. The small
red wire from he fuse holder or circuit breaker is also attached to the positive terminal.
Blown fuse or circuit
breaker
Replace fuse with 716 amp. fuse V4 x 1 V-i" Ig. Circuit breaker will reset itself when it cools off.
Fuses or circjit breakers seldom open or fail without a reason. The problem must be cor¬
rected. Checf for loose connections in the fuse holder. Replace fuse holder if necessary. A
dead short m.iy be in the cranking or charging circuit where the insulation may have rubbed
through and exposed the bare wire. Replace the wire or repair with electrican's tape if the wire
strands have lot been damaged. Note: Look for a wire pinched between body panels, burned
by the exhaust pipe or muffler or rubbed against a moving part.
Battery is dead or weak
Use a hydron eter to check the condition of the battery. The Specific Gravity (s.g.) should be
1.265 at 80° F, (1.215 s.g. minimum needed for cranking engine). The reason for the battery fail¬
ing must be cetermined. (1) Defective battery. Battery will not accept or hold a full charge. (2)
Short circuit. Check for grounded wire. (3) Charging system not working, either engine alter¬
nator or tricki i charger.
Trickle Charger. Check with multimeter. Charger 725-0578—input 120 V A.C., no load output
13.5 V D.C., rrted load current 1 amp. Charger 725-0507—input 120 V A.C., no load output 17.4
V D.C., rated I Dad current 1/2 amp.
Alternator (dual or single circuit) The charging system is an alternator located under the
flywheel. It is unregulated and rated 3 amp. at 3600 r.p.m. A diode (rectifier) is located in the
output lead just before the wire harness plug on the engine side.
To Alternator
The diode che nges A.C. to D.C. to charge the battery. A bad diode can either fail to charge the
battery or diSDharge the battery if the alternator is shorted as well as the diode. To test: (1)
Disconnect cliarger lead from the battery (small red wire). (2) Connect 12 V small test lamp be¬
tween the 3 amp. D.C. charge lead and the positive terminal of the battery. (3) With the engine
off, the lamp should not light. If it does, the diode and possibly the alternator should be re¬
placed. (4) Stcrt the engine. The lamp should light. If it does not,the alternator (stator) or lead
wire is bad and should be replaced.
Mechanical failure.
(Wires and switches)
The interlock system includes two mechanical activated switches which are wired in series in
the circuit us !d to energize the starter solenoid. While testing the interlock system, you will
make the mov/er temporarily unsafe by permitting the engine to be started with the blade and
clutch engag« d. WARNING: While testing, disengage the clutch, shut off the blade control, set
the parking brake and place the gear shift lever in neutral. Attach a wire (minimum 18 gauge) to
the positive lerminal of the battery and touch the other end to the small terminal on the
solenoid. If the engine does not crank; (1) There is a loose connection or poor ground. (2) The
solenoid may be bad. The solenoid can be checked by using a heavy wire (#8 gauge minimum)
and jumping lietween the two large terminals. If the engine cranks, the solenoid is bad. (3) If
the engine dees not crank when you jump the solenoid, have the starter motor tested by an
authorized ergine dealer. If the engine does crank, the problem is with one of the safety
switches, ignition switch or the wire between the fuse holder (or circuit breaker) and the small
terminal on tiie solenoid. Note: Look for a poor connection at the switches or a defective
switch. Replace if necessary.
Engine cranks
but will not
start
Throttle or choke not in
starting position
Check owner’s guide for correct position for throttle control and choke (if separate control) for
starting.
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