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Stalling L120

4345 Views 9 Replies 7 Participants Last post by  perryb
I have an '05 L120 with 355 hours on it. For the past 2 seasons, it stalls while cutting, once it gets warm. It seems that the cooler the day, the longer it cuts. I've replaced the fuel filter, fuel pump, used compressed air to blow out the fuel lines, ran it with the gas cap loosened right off, and even let my local JD dealer (where I bought it) have a go at it. $148 later, I had a new intake manifold gasket (o-ring?) but still the same problem. Some days, I can start it up, and it runs rough, so I let it sit at 3/4 throttle for about 5 minutes, until I can hear it smooth out. That seems to help. Other days, like today, it runs great right off the bat, but I got 20 minutes out if it. Since then, I've let it sit for 5 to 30 minutes (not all the way cooled down) and it goes for a minute or two. It almost seems more electrical than fuel based. It runs like a charm, and then it suddenly bogs down, or stutters, and once that happens I have 10 seconds or so before it snuffs completely. I've talked to my JD dealer since they had a go at it, I've emailed John Deere and no one seems to know what my problem is. But they are more than willing to keep taking expensive guesses at the thing.

I've been all over the net, and this seems to be a problem other JD 100 series owners are having. I am more than willing to pay to get it fixed, but I am hoping to pay just one more time. And I gotta tell you, I've had Honda, Gravely, Snapper/Kees, and even a p.o.s. Noma, and they all were tons better than this JD.

If anyone has any ideas on what I can try next, I am all ears. Thanks.
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Ahh, one of those "not there all the time" problems--the worst.
Heat seems to be the key factor, although it sometimes starts up rough, so yes it does seem to be electrical, but not sure. Looks like you've covered the fuel section pretty well, that leaves air and spark. Change plugs recently?
carb been taken off and cleaned? any air restrictions? spark plug wires ohm out ok? Might have to take some voltage measurements when this happens to see where the charging system is at. A bad voltage regulator (heat) can sometimes do this.
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sounds like it may be a coil going bad

It sounds like you've been very paitient. Don't give up now, just give some of the experts here time to figure it out.

I have had great help with repairs to my GT275, I hope your experience is the same.

Good Luck,
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Before I leave a long winded response does it have a B&S 20 hp Intech in it?
ignition system is what it sounds like... could be plugs... could be wires... could be the coil.

My old L120 had occasional such problems on one cylinder when some grass would get caught in between the spark plug wire and the shroud that it comes out of, or some grass and debris on the spark plug outside (ceramic white) insulator. It always seemed like there was not much dirt there, but I'd pull a few blades of grass out, or wipe the insulator - restart it, and viola! That little bit of dirt is exactly what it was. It happened only occasionally, but I imagine you have a leaking electrical system problem. Insulators sometimes loose some of their insulating properties when they get hot.

Give it a try - next time it happens - pull the boot off the plugs, wipe down the plug and the boot, move the wire in and out of the shroud a bit to dislodge any grass clippings and other dirt from in between the wire and the shroud - and put them back on the plugs and restart right away to see if that did it.
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wow...I've posted on a similar site, and get very few hits, if any. This is pretty impressive.

yes, heatman, it is the B&S 20 hp Intech.

I don't know why, but I have always suspected the coils. I've been meaning to do a spark test once it dies, but usually I am looking for matches to set the thing on fire, and have no interest in any diagnostics.

Yesterday, it stalled 4 times. The last time I tried it, it barely ran, and in fact had to restart it 3 times to get it to keep running. That third time, I ran it with just about full choke, and it sputtered away for 3 minutes or so, and then I took the choke off. It ran like a charm, ran for an hour, problem free after that, until I was done. It was still running like new when I parked it. This is a problem that comes and goes. It seems to be worse on warmer days. The plugs are new this year, and clean as a whistle after 40 hours on them.

Thanks for all the input on this. To be honest, when it cuts, it cuts well, and I'd like to stick with it. It's just getting a little tough to love my JD these days.
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sorry, wally2q, somehow I missed your posting there.

I have done that too. I am kind of obsessive compulsive about keeping everything clear of grass clippings, and have checked the plug wire boots. That doesn't seem to be it.

And for others who complain about the deck spindle/bearings? They really are low quality, but on the up side, they are cheap. My local JD dealership keeps them right up by the counter, so you know they sell them often.
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I have emailed John Deere about this issue, and pointed out everything I've tried. Man, they were helpfull. I was asked to continue working with my local JD dealership until I resolve my issue. At $150 a crack, this is going to turn out to be one expensive mistake of a purchase.
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