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Can anyone tell me if this problem has something to do with the auto-choke?

I am trying to fix an old (15+ years?) Husqvarna 6021P push mower that has a Kohler Courage XT-6 149cc engine. It had all original parts and was running poorly at the start of the summer. At that time, I discovered for like $2 more, I could get a replacement carburetor, instead of a rebuild kit, so I did. It has been running fine until recently. Now it is flooding on restarts. When the engine is cold, it starts and runs great. Once up to operating temperature, if I shut off the engine, it won't restart. It floods the carburetor when trying to get it started again. I think it may be related to the auto-choke.

Before I spend more money, how do I confirm whether the problem is related to the auto-choke?

Click above & scroll down page to XT6 & see Troubleshooting, let us know how it goes, thanks Mark

Sounds like a choke issue to me. Take the air filter off and look and see if it’s closed. How long is the engine shut off before you try to restart it?

When I run the mower to operating temperature and shut if off, then remove the air filter, the butterfly is usually in a halfway open/closed position. Its only off for a few minutes when I try to restart the mower and it begins to flood. If I use a finger to fully open the butterfly, one yank of the rip cord, and the butterfly goes half closed again. I wind up coming back hours later or even the next day to get it to start again.

I scanned through the recommended PDF file. The choke mechanism is some kind of sealed unit. I don't know what I can do with it, if anything. I see replacements on the internet for like $26, but I didn't want to spend that if there was something else I should be looking into first.

JStevenP said:

When I run the mower to operating temperature and shut if off, then remove the air filter, the butterfly is usually in a halfway open/closed position. Its only off for a few minutes when I try to restart the mower and it begins to flood. If I use a finger to fully open the butterfly, one yank of the rip cord, and the butterfly goes half closed again. I wind up coming back hours later or even the next day to get it to start again.

I scanned through the recommended PDF file. The choke mechanism is some kind of sealed unit. I don't know what I can do with it, if anything. I see replacements on the internet for like $26, but I didn't want to spend that if there was something else I should be looking into first.

Click to expand...

This engine uses a vacuum choke pull off doesn't it?

VegetiveSteam said:

This engine uses a vacuum choke pull off doesn't it?

Click to expand...

From what I have read, it is a choke that contains an internal coiled spring (sealed closed with rivets), and the spring behaves like a thermostat. It is mounted to the muffler on the right side of the engine and the heat from the muffler is suppose to cause the internal spring to expand. There is a rod that extends from this sealed unit across the front of the engine over to the left side. So when the internal spring expands, it is suppose to rotate the rod. On the left side of the engine, the rod connects to a lever on the carburetor and the lever, in turn, opens/closes the choke. It's acting like the coiled spring is no longer responding to heat, but with it being a sealed unit, I cannot verify that to be true.

Yes it is a sealed thermostatic spring coil unit on the muffler but there has to be some mechanism that partially opens the choke before the spring unit on the muffler gets warm enough to fully open the choke. The early Kohler XT engines used a vacuum diaphram pull off or relief to do that partial opening of the choke while the engine warmed up. Once the thermostat coil on the muffler got warm enough, it overrode the vacuum relief. Later XT engines used governor tension to partially relieve the choke. Does your system look like the diagram below? Item C is the vacuum relief I was mentioning.

If this is the system you have, notice the item circled in red below and shown again in another picture below that. That black plastic flag I'll call it, is able to be removed from the shaft and can be turned to change the clock position to add spring tension when the spring gets older and looses some tension. If you take it off, don't twist it. That flag and the shaft have splines to keep that flag from moving on the shaft. It needs to be pulled straight off so not to damage the splines. You could try taking it off and moving it a spline or two to increase the spring tension. There is also a pretty simple trick done with the vacuum relief that takes up some of the slop those can develop over time. I can go into that later if need be.

Yes, that diagram is accurate to my setup. So if I make the suggested adjustment, and I do so while the engine is cold, I should rotate the black flange just enough so that the tension is holding the butterfly closed, right? I mean, if the engine is cold, I would expect the tension to hold the butterfly closed and as the engine heats up, hopefully the spline will rotate the black flange in such a way as to open the butterfly and keep it open during operating temps. Am I understanding you correctly?

Yes. You have to pull the black flange off the shaft and then reinstall it in a new position with just enough tension close the choke. And again, pull if off. Don't twist it.

That flange is on there.... It doesn't want to come off. I hesitate to give it a shot of WD40. Maybe if I remove the entire choke mechanism and then soak the end where the flange is attached in some boiling water??

I also took a closer look at that vacuum diaphragm that you mentioned earlier. I noticed it had Trox head screws so I dissembled it. It was quite dirty inside, so I cleaned it and reassembled.

JStevenP said:

That flange is on there.... It doesn't want to come off. I hesitate to give it a shot of WD40. Maybe if I remove the entire choke mechanism and then soak the end where the flange is attached in some boiling water??

I also took a closer look at that vacuum diaphragm that you mentioned earlier. I noticed it had Trox screws so I dissembled it. It was quite dirty inside, so I cleaned it and reassembled.

Click to expand...

If you take it off you might be able to grab the rod and slide the support bracket sharply toward the flange sort of like a slide hammer a few times and see if that loosens it. Not too hard because you don't want to break that bushing in the support bracket. You might be able do something similar with a pair of curved jaw vice grips. Tighten them just enough so you can slide them down the rod toward the flange and possibly tap it off that way.

FYI, it's not uncommon for me to work 70 hour weeks, which makes it hard to be readily available to respond to this forum. I apologize for the delay and appreciate your continued advice.

I was able to successfully pull and reattach the flange from/onto the spindle in order to add tension that would hold the butterfly closed when the engine was cold. It was working in the sense that the butterfly was closed on cold starts and being opened at operating temperatures. Maybe not fully opened, but at operating temps, the butterfly was definitely opened more than it was closed. Unfortunately, this did not solve the problem. In fact, is getting worse. The carburetor is now flooding even when it is cold. It was only flooding when trying to do a restart at operating temperatures, but now it is flooding whether the engine is cold or hot. Assuming I goofed up, I returned the flange back to what I believe was the original position on the spindle. The carb is simply flooding all the time now, whether it is a cold or hot restart. Well I'm glad I didn't waste money on a new auto-choke.

Now I'm thinking that maybe the float is hanging up. However, it is a brand new carb. I just got it like 3 months ago. That's 12 weeks of use at approx. 1 hour per week or only 12 hours of runtime on that carb. I shouldn't be having trouble with it. Several times I have rapped on the outside of the bowl with a screwdriver handle. I want to see if I could free up the float, if it is in fact hung, but with no joyful results. I hate to think I have to crack the seal on a brand new carburetor.