Small Engine Problems? Ask an Engine Mechanic for Answers ASAP
That will be the engine number. Under the seat there should be a plate or sticker with an MTD number. Having this will allow me to look up the wiring diagram so we don't miss anything.
Do you have a voltmeter? It's possible that your charging system isn't working for some reason. We need to check the voltage across the battery both running and non-running. With the engine off and switch on, you should have 12 or so volts at the battery. With the engine running, there should be a 1.5-3 volt increase.
Generally speaking, when there's a voltage drain, I tend to suspect the ignition switch. The simplest way to check for voltage drain through the ignition is to start off with a fully charged battery then put the voltmeter on it every few hours for a couple of days and watch for a drop.
As yours will let you mow 2 or 3 times over two or three weeks, I tend to think that there's a charging problem myself. There should be wires coming out from under the flywheel that go into a plug. I'll need the MTD numbers to be able to tell you how many and what color they are, but if you can check that they're in one piece and all connectors are connected that will help to narrow things down. If the wires are all in good shape, then other problems might be the ignition switch, flywheel magnets, stator assembly, rectifier and regulator.
If it is a charging problem and if you have or can get a voltmeter we can trace backwards until we find the trouble.
You have a 12 volt system.
Do the headlights work when the battery is charged up?
I believe you're going to be in need of an ignition switch. With the key switched off and the battery charged, check for voltage at the starter and solenoid.
The solenoid could be under the seat, under the dash or under the frame, it's hard to say without knowing for sure which mower you have. What you can do to find it is follow the battery cable from the starter and it will lead you to it. It will be a small metal box-like thing with 2 battery cables running into it, one from the starter and one from the battery or switch. It may also have a smaller wire attached. The starter is on the side of the engine, it's the cylindrical object mounted to the rear and will have a cable bolted to it.
There should be no voltage reading at the starter or any post on the solenoid with the key switched off.
If there's no voltage to the solenoid with the key off then there's no voltage leak. First thing to do though is check the voltage at the battery and see that you have 12 volts with the engine shut off and a jump of a volt or two when it's running.
With the key off, there should be 0 voltage at the solenoid. With the key on there should be 12 volts at the solenoid.
At the battery, there should be at least 12 volts with the engine not running. With the engine running, there should be 13-14.5 volts.
This tells you that the charging system is working so we can pretty much rule that out. If you follow the cable from the starter backwards it will take you to the solenoid.
The ignition switch is what you need to focus on if you can't get to the solenoid. It's easiest to remove it so you can see what's what. The plugs should be marked with some letters. What you need to establish is which one the battery is hooked to. With the key switched off, that should be the only post that has current. If you have a continuity tester, you can check it easily with the switch disconnected. You can test it with a voltmeter too, it's just a little harder to get the test leads onto bare metal.
No. You don't need a new starter. The problem we have to diagnose is why the battery loses it's charge.
To test the switch you have to put one lead of the tester on the battery post on the switch with the battery hooked up to it so that you have power to the switch. The other lead you will put on each post on the starter, with the key turned off, and look for voltage. There should be no voltage at any post on the ignition switch other than the one with the battery lead.
If you want to, you can just replace the switch and see if that doesn't solve the problem. Thanks, PK.
Just hit accept and that will pay the $15 you put up.
I'd suspect the switch myself as your problem seems to be one of a voltage leak and it seems to be from the key switch. But replacing the solenoid will give you a new solenoid so that won't hurt anything. Thanks, PK.