mower stalls after an hour

I'm not sure the battery is the issue. Long as it spins the starter, over at a decent rate, the engine produces its own spark via magnetos.

#1: Be sure that all wire connections are clean and tight. Do this anyway just to eliminate it as a possible cause.

If the issue is the starter won't spin the engine, try swapping in a known good battery for a few test starts/runs. If it operates OK, then battery, or relay, or switch is the issue. I had a battery once that would short internally when load placed on it. Odd, but it acted similar. Voltage was OK, but loaded, wouldn't turn starter. If the same thing happens with a known good battery, then look to the starter, starter switch, or relay. Try to jump known good battery direct to starter. If that works OK, then likely its a switch or relay. If that doesn't work the starter has an issue.

Hope some of these ideas might be helpful.

EDIT: This applies only if your engine is run by magneto generated spark. You didn't mention what engine this was.

Sorry, but IMHO, 12.6V at the battery with the engine running (presumably right after starting the engine, which is right after charging the battery with a battery charger) means that there is a problem with the charging circuit on the mower. It should be at 13.5-14V or so. And mowing for an hour after fully charging the battery, then it dies and nothing works until you charge the battery again follows along with this. Once the battery is charged, it sounds like it's working fine, in that it starts the mower, and runs the PTO for that hour until the battery is discharged.

I would suggest looking at the charging circuit, there could be a loose or disconnected wire,corroded connection or a problem with the regulator or physical components on the engine (for example, some engines, the magnets for the charging circuit can fall off the flywheel).

First check the wiring, because it's easy and doesn't require much disassembly, then look at videos on testing the charging circuits on small engines to see how to test/fix them.

dave_r said:

Sorry, but IMHO, 12.6V at the battery with the engine running (presumably right after starting the engine, which is right after charging the battery with a battery charger) means that there is a problem with the charging circuit on the mower. It should be at 13.5-14V or so. And mowing for an hour after fully charging the battery, then it dies and nothing works until you charge the battery again follows along with this. Once the battery is charged, it sounds like it's working fine, in that it starts the mower, and runs the PTO for that hour until the battery is discharged.

I would suggest looking at the charging circuit, there could be a loose or disconnected wire, corroded connection or a problem with the regulator or physical components on the engine (for example, some engines, the magnets for the charging circuit can fall off the flywheel).

First check the wiring, because it's easy and doesn't require much disassembly, then look at videos on testing the charging circuits on small engines to see how to test/fix them.

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Thanks for the info.! I found the rod on top of my carb. had fallen off, I need a new c clip. I think that made it stall, my mower idles a little rough to begin with. I found the back of the key switch lugs really rusted. Would a John Deere brand last any longer than an Advance Auto or Lowes one? I did add dielectric grease but the lugs still rusted.

mlizotte said:

It's posted under the question. That way I don't have to post it each time.

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Respectfully, just saying something like "It's the tractor & engine in my signature" would make that much more clear. Otherwise people have to assume what machine you're talking about (you might have several, signature may not be up to date, etc). And if someone is on a mobile device, using Tapatalk, they may not see your signature at all.

Tractor-Holic, the carb solenoid closing as the battery voltage falls too-far was my thought as well, if it has one of those solenoids. The battery shouldn't be discharging while mowing, so something is going on with your charging circuit, which may be eventually causing other problems as the voltage falls.

mowergene said:

My guess is that it's your voltage regulator. Shopping online, you'll find they don't break the bank. I just bought one for $22.

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https://forums.yesterdaystractors.com/ttforum/viewtopic.php?p=624889 Thanks, here's a pic. of the wiring system. I read 90% of the time it's that. I just switched to a good battery. 12.83 volts key off and 12.78 volts running. Can you test the reg. off the mower?

mowergene said:

If your "idiot light" for the battery wasn't coming on before, hook up the new regulator and give it a shot. When you turn the key to ON the light should come on. Once it starts, the light should go off. If it does, you'll know it's charging.

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There's no light or no amp meter. It's like driving an older vw bug. lol

If the battery is putting out less voltage running, it looks like either your stator isn't working or the VR. The regulator is the more suspect of the two. That's really all I know to tell you. I'd buy the regulator unless you're flat broke. They're an electronic device and don't like all the heat off the engine!

Replace that c-clip as you know its a problem, but it's not the solution you seek, as it only involves the engine and not the charging/electrical problem you have.

I'd first do a load test on that battery. Even if only a day old, it could be a bad cell within or old enough that it just won't take a charge anymore. I've had it happen to me before. Good known battery when removed for winter and connected to charger-maintainer over winter. All ohmmeter tests showed good 12.60+/- volts WITHOUT A LOAD, but once connected back up, it started the mower this spring and even showed a charge, but next couple times I'd need a jump to get mower started.

Removed battery again and had automotive store I bought from(NAPA) do a load test. Wouldn't take or hold a charge anymore. It was a $100+ battery with 6yr pro-rate battery. It was only about 3-1/2 yrs old. Exchanged after getting pro-rate price for the cheapest that NAPA had.

I'd also change out the ignition key switch if it has any serious age or rust like you say on it. It doesn't need to be from a dealer, as they don't make them to start with. It probably comes from Littelfuse/Hencol or it might even be a coded tumbler lock(like a house key). Remove it and it should have some #s on it and usually at a much lower price on Littelfuse site, which bought out Hencol(a switch my mower used). It's how I found my ignition switch which I changed out during the winter as my switch wasn't getting good "start" contact after 29yrs. I got my switch at NAPA(City Parts) as they offered no cost to me if it didn't work, or was different than what picture showed. It was exact and more than 1/2 price that dealer wanted.

If most "non" charge problems happen on an engine it's usually the voltage regulator as it's the cheapest to replace and easiest to get to in most cases. You can do a voltage/charge/continuity test on the regulator still hooked up with ignition switch to "on" position, or with engine running, by going through a proper sequence of steps and what the voltage measurements show. Doing this will also show how your charging system is and if its functioning properly.

Do check all grounds to be sure there's no problems of rust buildup and positive contacts, along with checking all connectors of good contacts. I like using some dielectric grease also to help with any moistures and helping keep rust away.

Replace clip for carb found one at Lowes. I brought a reg. and key switch with good reviews, from Amazon. Did the reg. first I get 12.5 volts at each lug now, with the key on. But it didn't fix the voltage problem. Replace the key switch, now the voltage is 13 volts key off and 13.87 volts while running. So it looks like it's charging now. I heard the cheaper reg. may not last more than five years. The OEM run about $85.00. Thanks for all the help! Hope this info. helps someone else.

mlizotte said:

Replace clip for carb found one at Lowes. I brought a reg. and key switch with good reviews, from Amazon. Did the reg. first I get 12.5 volts at each lug now, with the key on. But it didn't fix the voltage problem. Replace the key switch, now the voltage is 13 volts key off and 13.87 volts while running. So it looks like it's charging now. I heard the cheaper reg. may not last more than five years. The OEM run about $85.00. Thanks for all the help! Hope this info. helps someone else.

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I believe the voltage regulators, being electronic, are sensitive to heat. I've relocated one with success. Check the steel that yours bolts onto for heat. Warm is probably fine where hot is not.