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Discussion Starter #1
Ok here's a question for the Kohler experts in the house.

I was out mowing with the comm12. After about 20 minutes, it started missing and spitting a bit. I stopped, let it settle, it did, kept going, after a few minutes started up again. Acted like fuel delivery. So I limped back to the barn, took some stuff apart, tested the fuel pump and line, opened the carb, nothing obviously wrong. Put it all back together, started up, after a few minutes, same deal.

After some fooling around, I realized that it runs just fine at idle or a little above. If I start to throttle up, it gets to a point where it starts complaining again. If I throttle back down, I get black smoke, then it settles down. When it's starting to act up, I can see spritzes of fuel coming out the carb intake (!).

I think I've got something going on where starts getting way too rich. I've adjusted the main jet all over the place, and that doesn't seem to affect it a whole lot, though if I crank it down too much, it just quits.

The sweetest spot for the main appears to be about 3.5-4 turns out, which is way too much according to the manual.

So what do y'all think? More crud in carb? An air leak or something? Should I expect to see fuel spray when it's running?
 

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Need to check the pickup in the tank as well. If you have water, or some other contaminate in there, that's gonna cause trouble.
 

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Sounds to me like either a fuel delivery or contamination issue. I'm not sure if you're running with a filter or not, but it doesn't take long for tank crud to make it's way thru the fuel pump and into the carb again. And if you're running with filters, not changing them out will result in similar problems - sans the fuel spraying symptom. You should definitely not be seeing any fuel spraying - unless you're in the midst of some lab testing program!
 

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Discussion Starter #4
It's true that this tank has some rust problems. I blasted it out some when I had the machine all apart, but I'm pretty sure it's not spotless in there.

But I do have an inline filter between the pump and the carb. It doesn't look too dirty. And when I disconnect the line at the carb and crank it over, I get good solid shots of fuel out of it. So I no longer think it's fuel delivery.

Water? Well, I don't think so. It stays inside when not running. Earlier today I drained the tank, and didn't see any water in the bottom of the bucket I drained it in to.

You should definitely not be seeing any fuel spraying - unless you're in the midst of some lab testing program!
Right. I still think there's something leaking in the carb, or something like that.

I have a spare K301 carb salvaged from a JD, maybe I should try that one.
 

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I've been in the middle of similar issues the last few weeks with my 5665. Thread is here: http://www.mytractorforum.com/showthread.php?t=306138

Sounds like a stuck float to me and possibly a clogged jet. A carb. tear down and cleaning is probably a good idea. Verify the float is level with the bowl gasket when inverted. Beyond that, I'd also be suspicious of the condenser. I'll be replacing mine early this week due to shutdown issues once hot.
 

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Discussion Starter #6
Hmmm. I didn't check the level of the float when I had the carb off, but I did check that the float and needle were moving freely. I think I'm still dubious about a leaking needle valve, as I would expect that to drown the engine when it's idling. But it idles fine, indefinitely, with no fuel leakage or anything.

I hadn't thought of ignition problems, but that's a possibility. I've seen condensors which go intermittent when you try to cycle them too fast. And there's the heat issue.

Well, ok, I guess I'll try the JD carb first, because I don't have a spare condensor to try. If that doesn't reveal anything useful, I'll come up with a condensor and try that.
 

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Hmmm. I didn't check the level of the float when I had the carb off, but I did check that the float and needle were moving freely. I think I'm still dubious about a leaking needle valve, as I would expect that to drown the engine when it's idling. But it idles fine, indefinitely, with no fuel leakage or anything.

I hadn't thought of ignition problems, but that's a possibility. I've seen condensors which go intermittent when you try to cycle them too fast. And there's the heat issue.

Well, ok, I guess I'll try the JD carb first, because I don't have a spare condensor to try. If that doesn't reveal anything useful, I'll come up with a condensor and try that.
Also try leaning out the main fuel jet as well as look the float over for pin hole or presence of gas inside it.
 

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One of my main mowing 5665's was sputtering and coughing last weekend and required the choke on to run remotely well. The in-line fuel filter between the fuel pump and the carb was the culprit - it looked relatively clean, but there must've been some sediment trapped there. When removed, the beast ran as intended. I would second the float check and another scrubbing of the carb interior.
 

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stuck float
The bane of my existence - stuck floats on K301s.

Need to start looking for one of those "refurbish" kits [assuming your time isn't worth as much as the cost of an altogether new carb].

try the JD carb first
Gravely mounted the carburetor in such a way that the choke wire pulls the carburetor "arm" in a really bizarre non-standard semi-circle.

I've got several old "junkyard salvage" Gravelys, with other manufacturer's carbs on them, where you literally have to adjust the carburetor arm BY HAND, while the machine is running, simply because there's no way that you could ever finagle the Gravely choke wire to pull on the arm in the direction which the other manufacturer had had it spec'ed.
 

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Discussion Starter #10
The bane of my existence - stuck floats on K301s.

Need to start looking for one of those "refurbish" kits [assuming your time isn't worth as much as the cost of an altogether new carb].
If you mean the new gaskets/needle/seat things, I put one of those in a couple months ago.
Gravely mounted the carburetor in such a way that the throttle wire pulls the carburetor "arm" in a really bizarre non-standard semi-circle.

I've got several old "junkyard salvage" Gravelys, with other manufacturer's carbs on them, where you literally have to adjust the carburetor arm BY HAND, while the machine is running, simply because there's no way that you could ever finagle the Gravely throttle wire to pull on the arm in the direction which the other manufacturer had had it spec'ed.
Humph. Well, ok, it didn't look that different, but I didn't look at it closely. Maybe that won't work after all.

The choke linkage is different, but for this experiment I don't care, just want to try it enough to prove that the engine is otherwise ok, and whatever it is, it's in the carb. I suppose I could take the carb off my 812 and try that one . . .
 

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That link NC_G gave is from the same place that I found solutions to the Walbro carb frustration I had with my M18. Until that was put up by Jepics i had tried everything - for 4 months to solve the hunting at WOT. I followed the details - it is so clearly laid out with pics - easy to do - no problems since. I just copied that link and put it in my K301 file for the 8122.

Regarding your symptoms John - They sound exactly like i experienced with my M18 at one point. It turned out to be and ignition module that had gone bad. Now i know you are dealing with points and condenser, not a magnum, but I'm just saying those same symptoms can be ignition related not fuel delivery. Particularly when they seem to be related to the engine temperature.

Also if you know there might be some rust waiting to sabotage you, be certain your fuel filter stops very small debris. RichardTx covered it somewhere on here. All fuel line filters are not the same. Use a NAPA 6011.
 

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If you mean the new gaskets/needle/seat things, I put one of those in a couple months ago.


Bluegoose reminded me a couple of weeks ago that if you put a new needle in the old seat it may not match because sometimes the needle is smaller.
They roll around and sometimes get stuck causing the problems that you’re experiencing.
Let me know if you need another carb.
We have several rebuilt Kohler #26 and #30 ready to go.
Jake
 

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Discussion Starter #16
Huh. I *think* the rebuild kit had both needle and seat new, but I'd have to go through the bag of removed parts to be sure.

I'm still puzzling over how that kind of problem (needle not seating, so causing overfill of bowl) would cause it to idle fine, but start to act up under load. I would think it would totally flood at idle as well.
 

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Given heat causes the problem.. I'd look at ignition break down. Seen it more often than I care to admit. I even went through a Briggs carb last year just to realize.. points and condenser were wonky. New breaker-less coil and the owner is super happy.
 

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If I was in your shoes I would go through the fuel system again and install new points condenser and coil.
That way you wouldn’t have to be chasing that dog for a long time.
 

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Huh. I *think* the rebuild kit had both needle and seat new, but I'd have to go through the bag of removed parts to be sure.

I'm still puzzling over how that kind of problem (needle not seating, so causing overfill of bowl) would cause it to idle fine, but start to act up under load. I would think it would totally flood at idle as well.
My recent experience is that it won't even start in that condition.
 

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Like Jimmy said - because related to heat - probably not related to fuel delivery. Think I heard that somewhere before.
 
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