Simplicity tractor: intermittent electrical problem

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Old 09-14-18, 08:33 PM
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Simplicity tractor: intermittent electrical problem

I have a Simplicity Landord tractor (1692784) with a 16 HP Briggs Vanguard V-twin engine (Model 303777, type 1111A1, code 96112011). The last few times Iíve used the tractor it has died once per use. It takes about 1.5 hours to mow my lawn. Iím just going along and it suddenly just stops running. I go to restart it and I hear only a click (presumably the solenoid)óthe starter does not turn over, the various dash lights do not illuminate. I wait maybe 15 or 20 minutes and then it starts just fine and runs fine. I havenít yet done any voltage measurements or circuit tracing when the tractor will not start. The battery was replaced this spring so itís hard to believe the battery is the problem. I replaced the ignition switch but still have the problem.

What else should I be checking? This tractor is about 19 years old and the engine has about 750 hours on it.
 
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Old 09-14-18, 11:19 PM
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You are losing connection through a spot that is making connection enough but after it overamps a while, it gets too hot and loses it. It could be the fuse int he fuseholder, or the negative cable where it attaches to the frame or motor, or several places.
 
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Old 09-15-18, 05:58 AM
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As Cheese said, make sure all electrical connections are secure. You need a electrical multimeter to measure conditions, if securing connections does not correct your problem. Having a schematic and wiring diagram for your machine is extremely helpful. The multimeter should be able to select ohms and AC and DC volts/amps as a minimum. You need to measure the battery voltage when the engine is running (13-14 vdc) and when cranking the engine (<10vdc). Once you post these measurements, I can give you further directions.
 
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Old 09-17-18, 07:25 PM
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OK, so I made some measurements with my DMM connected to the battery terminals. With no load I get 12.9 V, while cranking 10.5-11.0 V, while idling 13 V, wide open throttle 13.95 V. Those numbers all seem to indicate the charging system is OK. While I was nosing around under the dash panel with the key off I apparently shorted together the studs on the solenoid with my inspection mirror (yeah, I know, disconnect the battery first) because the starter briefly turned over. My first thought was, crap, I hope I didn't fry something. But when I looked around the only exposed electrical terminals I could see were the studs on the solenoid--everything else is encased in plastic connectors. Shorting those terminals together shouldn't cause any harm.

But after that episode the situation has changed. Unloaded battery now shows 12.6 V, while cranking is still 10.5 - 11.0 V. But at idle and WOT the voltage is 12.6 V, which would indicate the battery is not charging. And now when I turn the key I hear a click shortly afterward (1 sec or so). The clicking is coming from the 20 A circuit breaker that feeds everything except the starter motor. So something is drawing a lot current. Any suggestions what might be doing this? No fuses on this machine.

Also, I checked all the ground connections I could find. I didn't really find anything I'd call loose. I cleaned and tightened several of them, though.
 
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Old 09-18-18, 12:01 AM
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Ok, circuit breaker rather than fuse then on this one. Get a 12 volt test light and disconnect the negative battery cable and connect the test light between the cable and the battery post. Unplug the fuel shutoff solenoid if equipped and turn the key on. The light will come on if there is a place for current to go. If the light is on, unplug different connectors until you get one that turns the light out. That will help you narrow it down. I don't know if this model has relays, or a voltage regulator, but try these things and see where your current is going and causing the breaker to trip.
 
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Old 09-18-18, 12:51 PM
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One Down, One to Go

Since I don't have a 12 V trouble light, I used the resistance setting on my DMM to look for low resistance paths to ground. I was able to isolate it down to the anti-backfire solenoid on the carb. The wire had been routed through two overlapping pieces of stamped steel that form the engine cover. Over time and with vibration one of the metal pieces had cut into the insulation and created an intermittent short to ground, which then tripped out the circuit breaker. Splicing and rerouting the wire was all it took to fix.

I still have the problem where the measured battery voltage is independent of engine RPM, which would indicate the battery is not being charged. I checked the AC voltage of the alternator stator and get about 28 V at WOT, and 14 V at idle. So the alternator seems OK. To check the rectifier/regulator I need a shunt which I do not have. Could it be anything other than the rectifier/regulator? I see the Chinese knockoffs go for only about $10.
 
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Old 09-18-18, 05:58 PM
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To check the regulator, just unplug the single wire coming out of it and check DC voltage there with the engine running full speed. Since your AC voltage is known to be good, then if there is not 15+ volts on that wire with the engine running, the regulator is bad.
 
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Old 09-21-18, 05:25 PM
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Bad Rectifier/Regulator

I neglected to mention I had already done exactly what you suggested--measure the voltage at the regulator output. I got a variable output in the range of 0 to minus about 2 volts. But somewhere I had read if the battery voltage is less than 5 V the regulator will not work. I figured when the output is not connected to anything then that would be the same as a battery of zero volts. Anyway, I bought a new regulator/rectifier and I'm back in business.

I can't help but think that the shorted wire must have wiped out the regulator/rectifier. I mean, what is the likelihood of having two unrelated electrical failures at the same time?

Thanks for all your help with this.
 
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Old 09-21-18, 07:41 PM
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You're probably right. Those regulators go bad often enough anyway, but the short created an over-amp situation and it overheated the semiconductors. Glad you got it fixed!
 
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