Zero turn mower only restarts after sitting a couple days

[ChrisSl789]

Thanks for all the useful replies. The voltmeter tracing the circuit is definitely something I will try next time I mow and can't start again. Will also try removing the gas cap for a few minutes after I mow next week as that will be easy. I will update if I find anything that works. I do regularly change the spark plugs and fuel filter, and this problem has been going on for a couple years with those replaced.

It behaves most like a problem with the safety start circuit. My primary suspicion was a safety switch, and tracing the circuit will help find that. The thing that confuses me is that it will fix itself after a couple of days-- never one day but always two or three days it starts again fine. I mowed on Friday, couldn't start on Saturday, and it started no problem today (Monday). I didn't do anything in between. Today I engaged the PTO to start the blades and let it run for a few seconds. After just running the blades but not moving, it started up again no problem.

It's either MZ6128ZT/96613101 or MZ6128ZT/96613102. Bought 8 years ago. I can google a wiring diagram.

Thanks again and I will post again if I figure it out.

 

[mini14]

Those plunger safety switches stick shut

 

[Bentrim]

Battery, Key switch, PTO switch, "Handle" switches, brake switch, Starter solenoid. Can't remember which exact order the handle switches are or if the brake switch is before or after the handle switches. Take a test light and trace in that order. Usually most of the safety switches have 4 terminals if they do two are starting and two are run. Note PTO switch has three rows of terminals usually the "common" is marked. Switch down either the center row has continuity and the other does not. Pull switch up and again test common to the other row of terminals should be opposite of off. Be sure the handle switches and the brake switch are moving and are in proper position (plungers moving in and out and the lever is pushing the bottom). As a TEST take a wire from the battery to the small post on the starter or solenoid if it cranks you have a safety switch problem. Some Husqvarna mowers also include the seat switch in the safety circuit so don't forget to include it in testing. If you have a wiring diagram in the op manual (some do and some don't) follow that for the exact order and color of the wires. If you don't have a wiring diagram some times the parts book may include it go at www.https://www.husqvarna.com/us/support/manuals-downloads/ and look up your model. Be sure to do the testing when unit won't start and you are not pressed for time so you can have time to thoroughly test the circuit. Good luck at find the mystery no start.

 

[dennis morgan]

I have been having a problem restarting my Husqvarna MZ6128 zero turn mower after running it for a few hours. This has been happening for a couple of years now, so I know how to work around it but would like to address to problem . It is a real puzzle to me, and any thoughts would be welcome. Here is what I know:

1) When I finish mowing, or if I have to stop in the middle, my mower will not restart. When I turn the key, I get nothing. No clicks, no engine turn over. Nothing. I have been testing this for a few years after I finish mowing and it is always the same... nothing.
2) After it sits for a a few days, it will start with no problem. My "solution" is to always mow my entire yard (which takes a couple hours) and park it when done. Without fail, it will be fine the next time I need to mow in a week or two.
3) I don't think it is related to heat. I mowed the lawn on Friday afternoon, and tried to start it on Saturday at noon and got nothing. If I wait until Sunday or maybe Monday, it will start with no problem.
4) When it has been sitting long enough to start, I can start and restart it as many times as I want as long as I don't move it (tested this many times over the last few years). However, if I drive a short distance (e.g. from the barn to the house, 75 yards) it will most likely not start again (I don't test this very much since I can't mow for a few days).

Any ideas on what could be causing this? Or other things I should check? I can't think of anything where letting it sit for one day doesn't "fix" the problem, but sitting 2 or 3 days does allow it to start again.

get an ohm meter and check the switch operation on each switch, also the keyed switch.. spark plugs and fuel has nothing to do with no start or clicking. first of all i would follow the plus or hot battery cable, the first switch is the relay, this one will cause the problem. this is a common switch to go out. cost about 12 to $15

 

[Ghost River Retrievers]

So yesterday late afternoon I went to the shed ... with wiring diagram in my hands ... to work on the Husqvarna. With the diagram, along with the advice provided on this forum, I felt fully armed, prepared and ready to do battle with that beast.
Of course, it started ....
But I'm ready for next time!

 

[CoyPatton]

Thanks for all the useful replies. The voltmeter tracing the circuit is definitely something I will try next time I mow and can't start again. Will also try removing the gas cap for a few minutes after I mow next week as that will be easy. I will update if I find anything that works. I do regularly change the spark plugs and fuel filter, and this problem has been going on for a couple years with those replaced.

It behaves most like a problem with the safety start circuit. My primary suspicion was a safety switch, and tracing the circuit will help find that. The thing that confuses me is that it will fix itself after a couple of days-- never one day but always two or three days it starts again fine. I mowed on Friday, couldn't start on Saturday, and it started no problem today (Monday). I didn't do anything in between. Today I engaged the PTO to start the blades and let it run for a few seconds. After just running the blades but not moving, it started up again no problem.

It's either MZ6128ZT/96613101 or MZ6128ZT/96613102. Bought 8 years ago. I can google a wiring diagram.

Thanks again and I will post again if I figure it out.

A dirty check of your starting circuit is to bypass every safety switch. Check that you have power to your starter from the battery (12.6v) then check if you get power to your key terminal on the starter solenoid. If you use a digital volt meter, you should make note of the voltage if any. DO THIS WHEN IT WILL NOT START. If you near the volts you got on your battery cable at the starter your issue is inside your starter—possible overheating issues.
If you zero volts or near it, then you have issue in the safety switch starting circuit between the key and the solenoid on the starter.
If the starter is not engaging (as I remember you saying in your OP) fuel is not your issue. If the starter is engaging and spinning the motor, then disregard the starter test above, and pursue fuel and fire issues.

 

[joebeck]

Had same problem with my Craftsman riding mower which quit starting after only nine hours of use. Turns out it was the coil in the starter solenoid. The wire inside the solenoid came unsoldered and after it cooled off it made contact again. Try tapping on the solenoid while key is in start position and see if it cranks. If there is no voltage to the small connectors on the solenoid then the problem is elsewhere. Also if the solenoid has voltage to the input side of the solenoid and you jumper the high current (large cable from battery) connectors it it still doesn't crank then there is a problem with the starter motor.

 

[ChrisSl789]

It turned out to be the blade engagement switch or what I call the PTO. A quick fix when it wasn't working was to engage/disengage the switch a dozen or so times and it would start running again. I have replaced the PTO and it is working normally again. Thanks again for all the ideas. I hope the replies help someone else who has a similar problem, but maybe a different root cause.