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Transcript:

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Hey everyone, and welcome back to the channel. Today, we're taking a look at a John Deere X300. A customer brought it in and said that it runs poorly and that it pops and cracks when it's under a load.

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So when he tries to engage the PTO, or when he's going up and down a hill—or anything that involves any power—it will start popping and cracking and running poorly. It kind of sounded the same way when I was pulling it in. We're gonna go through the full diagnostics on a John Deere X300—or any other model—if yours has a Kawasaki V-twin engine on it.

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Don't forget to hit that like and subscribe button as we go along. First, we'll get the hood out of the way here.

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I've got my noise cancellation turned off, so hopefully the crickets aren't bugging you too bad. Let's show you exactly what this thing does.

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Now, when I ran this thing in yesterday, it wasn't doing anything like that. It wasn't popping and cracking nearly that bad. It actually didn't sound horrible. Let's dig in and figure out exactly what's going on.

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One of the first things I like to confirm is that we're getting a good fuel supply when we're working on any running issue on an engine. We want to make sure that the fuel is good quality and that it doesn't have any water or anything in it.

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So we're gonna locate the fuel filter and the fuel line going to the fuel pump. That's this little circular thing here. It pumps it from this line from the back, and then it sends it here to the carburetor. If we take off the outlet side going to the carburetor, we're just gonna put a fuel line on it, and we'll turn this thing over and see how well it shoots out of there. You should get a very good flow. It should not just be trickling out.

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Let's see if I can't set it up to get a good view of it. Now, that's a decent flow. Much lower, and I'd probably want to address the fuel filter or something to that effect. It looks nice and clear, and it smells good.

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Now, we did service this—I think about three or four months ago. We would have checked all that out then. Everything still looks good. I haven't talked to the customer about what type of fuel they're using, but with it popping and cracking this bad, if there was an issue with the fuel, we'd see some sort of separation.

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This is one that I pulled out of a mower recently. You can see that there's a line of water at the bottom of it. You should not see any sort of separation at all. This one's extreme, obviously, but if you see even just a little bit in the bottom of your jar, if you put it in a clear jar, you'll want to drain that fuel and put some known fresh fuel in it.

We always use ethanol-free. This fuel—I'm gonna say it is good.

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Normally, that's not gonna be the cause of a popping and cracking issue, but if it has a bunch of water in it, it will cause improper combustion and can definitely cause some funky issues.

So we've got good fuel, and we know we’ve got spark because it's running—but let’s test both cylinders independently. We've got two cylinders. We've got one here, and we've got one on this back side. These should run independently of one another.

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So if I unplug one spark plug wire, the mower should run perfectly fine on one side. One of the easy ways to know if it’s a fuel-related issue is that if it's losing power and bogging down—also while you're doing this—and not so much that the popping or the cracking is bad, you can choke it just partially.

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Push that choke up just a hair, and if it starts to run better at any point as you're going up, then that's gonna mean the issue is fuel or air-related, and we could have just a plugged air filter.

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If your air filter is completely restricted, you will get a little bit of bad running. I mean, that thing’s just clean as all can be, so I'll leave it off of there. Still got a little bit of debris up there—we’ll want to blow that out a little bit first.

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If you're getting a bunch of black smoke and fuel smell, this choke could be stuck in the up position. I see that often, where once it comes up, it doesn’t come right back down—and this one actually seems like when I push it up, it doesn’t come right back down either.

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It does—it’s supposed to be spring-loaded. Once you come up, it should go up and come right back down. It seems like it does with the choke lever. When I was pushing it by hand a little bit further though, it was wanting to stay up. Working okay now.

Still a little sluggish—we’ll want to clean that out a little. You can just blow down through here with some carb cleaner and some compressed air usually, and free it up. I do have a video on taking this apart and actually removing and cleaning that choke also. I’ll put that up top.

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Let’s check this cylinder. I’m just gonna plug in a different spark plug and just hold it against the side so it does discharge as we're going. Right now, with this unplugged, we're gonna be running on that opposite cylinder.

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So how does it run? It appears that the opposite cylinder does not want to run at all.

Okay, so that means that there’s something going on with that cylinder, likely. Let’s try it backwards.

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We’ll remove this plug—oh, it’s really on there. Got that other side plugged back in. Remove this plug here. We’ll hold it against the block just like we were on the other one.

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Right, so it's showing us that something’s going on with this cylinder. It looked like we had spark there. We can test the spark while it’s off. I’m gonna use a spark checker and see what it tells me—just a little clip-on.

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It’s showing 0 spark at all. Unplug this other one again, just to kind of see. Zero spark, which means this cylinder definitely has an issue.

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If you're testing without a spark tester, it's pretty easy to do—just hold it to the side of the block while you're turning it over, and from the inside to the outside probe you should see a good spark. You want to insulate yourself—that way you don’t get shocked.

I’m seeing all kinds of spark there, which is very strange, as it was showing bad with my checker—and it wasn’t running, of course. Not one bit of spark is what the spark checker’s showing, even though it is sparking.

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Let’s take the plug out. This plug looks good. I don’t see any issues. Put a brand new one in—it’s the one that we were just using for testing. See what our spark checker says now.

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It showed good there for a second when I got that pop, but at first it showed bad. So we’re not dealing with a spark plug issue—we are dealing with some sort of either spark issue or an issue with the valve train.

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To me, it’s presenting as a spark issue because we’re showing intermittent coil voltage—or intermittent spark—with our spark checker. It’s usually pretty accurate. I don’t usually have any issues.

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Let’s see if it runs independently without this other cylinder now that we’re getting a little bit of action out of it. Got the other one unplugged. Right back to 0 spark.

So this is telling us we have an issue with the ignition coil or with the kill wire up underneath, or one of the kill wires of the tractor itself.

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Since the other coil is sparking okay and it’s not being killed out—it’s on the same circuit as this—so it’s not gonna be a safety issue or an issue with one of the electronics on the tractor. It’s gonna be something that’s on this engine itself.

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With it only being one cylinder and we're showing bad spark, we're gonna proceed that way. If you were showing good spark—even though we kinda saw it here, which is very strange—you would want to open up the valve train and figure out if you had a bent pushrod, or a stuck valve, or something to that effect.

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To get in here to where the coils are, we’ll need to take the screen for the flywheel fan off, and then also the bolts for the housing. These are T30 Torx. They're all the same size.

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We’ve got the fan, and then underneath there’s a little spacer also. We’ve got a 10 millimeter bolt here, here, and here on this side. This one’s gonna be a little longer because it goes into the oil fill tube. So that’s the long one out of the six we’ll have to take out.

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Take the air cleaner out. Looks like we’ve got two 10 millimeter bolts here. Still got that other spark plug hooked up. And this one is through the holder for the lines. Weird—it almost seemed like it was stuck in there. Not cross-threaded.

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Then we can take the fuel pump off. There’ll be two of these same screws. The whole housing is free. You can kinda pull this away and it comes up and off.

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Here we are at the ignition coils. I’ve already got this one unplugged over here. I’m gonna hold it against the block, and what we’re gonna do—since we know this is the side that’s not working—we’re gonna unplug the kill wire here, and that basically removes it from the rest of the system.

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This one is completely independent. If you do this and your coil’s working right, it will be hard to shut it off. You’ll have to either pull the plug or ground this back out, so be aware of that.

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But let’s try to start it and also test and see if we’re getting any spark without that kill wire. Absolutely nothing—which is, again, very strange, because when we visually inspected this side, we were able to see some spark on that plug.

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Let’s test the other side and see what it is getting, just for the heck of it. I’m gonna just ground out this plug, hold it to the side. So my spark tester was working. It went to high as I fell down here, but reset it. Showing good spark on this side with my spark checker, so the spark checker’s working okay. This coil’s working okay. This coil is bad.

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When you’re testing for this, you can check the gap in between the coil and the magnet, and also check the magnet for rust or anything that would impede getting space correctly. Everyone loves to sand or wire brush the magnet there. Got it all clean.

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And just visually inspecting straight down, I can see that there is a good space. It is not spaced extremely far, and it’s not extremely close. It’s not rubbing.

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We’ll take our two 10 millimeter bolts out—both the same size. We’re gonna remove this coil. This is a 21171-7047. There are a lot of them in a lot of different numbers, but they all cross back to the same.

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This coil is actually off of an engine that somebody changed the oil—I think it was the first or the second oil change for this engine—and they put the wrong oil filter on it. Engine started leaking oil, or leaked when it was sitting there. They ran it and locked it up. These are basically new coils.

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I’m just gonna show you for testing purposes that that is what’s going on. We will get a new coil for the customer. But again, basically brand new.

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We’re just gonna space it with a business card in between, just like such. Perfect. If you want to use a spacer or a feeler gauge, 0.010" (ten-thousandths) is where you want to be.

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Just gonna put a little bit of anti-seize on there, make sure that they don’t seize. Only thing I don’t like about using anti-seize is it gets everywhere.

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Just gonna rotate and get our card out. Visually inspect again. Our coil—properly spaced.

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Now let’s plug it in. I’m gonna hook up the kill to begin with, because this coil should work. I don’t want to have to deal with trying to shut it off once it starts.

Let’s see what our spark checker says now. Look at that—green and it starts.

This other plug is unplugged, but it could have been sparking back on that other spark plug, because I had it sitting right there. It’ll jump to that other plug.

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Now we’re just running on this side. We’re getting that spark now. We know the valve train’s good because the other one’s unplugged.

I’ve got the air filter on just so it doesn’t suck anything from when we engage the deck. Let’s see how this thing runs with both cylinders going.

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Well, there you have it—a nice simple fix for a failing ignition coil that, for some reason, was still showing some spark but was not showing as a good spark with the spark tester.

So the spark tester was working because that spark was actually not present—or it was low enough that it wasn’t reading that it was present.

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Very good spark checker. I like those a lot. Kind of pricey, but they do really come in handy for all electronic ignition issues.

Anyway, hopefully this has helped you if you had the same or a similar issue on any of your V-twin Kawasaki engines, whether it’s on this John Deere X300 or any other make or model.

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Don’t forget to hit that like and subscribe button if you enjoyed the content. Thank you for watching.

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Frequently Asked Questions (FAQ)

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Q: Why does my John Deere X300 pop or crack under load?
A: This is often caused by ignition coil failure, bad fuel, or a stuck choke. In this video, we show how to diagnose and fix the problem step-by-step.

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Q: How can I test if my mower has spark?
A: You can use a spark tester or visually test spark by grounding the plug to the engine block and turning it over. This video explains both methods.

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Q: What engines are covered in this guide?
A: While we demonstrate on a John Deere X300, this guide applies to most riding mowers with a Kawasaki FR or FS V-twin engine.