That might be true, on the vibration. This engine is 24 years old lol; it's still running strong when I can keep everything firmly connected. I HAVE had issues with the engine mount bolts coming loose and have to tighten them up regularly. Discovered when we inherited the tractor from hubby's grandma that the engine was being held to the frame with only three of four bolts, and those just regular bolts, not the OEM engine bolts, if it makes any difference. Got four OEM B&S engine bolts on eBay, and the lock washer that was supposed to go on one of them, but that one somehow came loose and fell out someplace. So back to a regular bolt in that hole. But I periodically tighten those bolts because they do seem to work loose; there is definitely some vibration going on but don't know if it's related to the PTO or not. No problems engaging or disengaging; no unusual vibration. So probably a good case for the carb bolts working loose; once they loosened (before I discovered the problem with them and the engine mount bolts) maybe they started wearing on the bolt hole threads??? Anyway, back to current problem. The bottom screw on the carb mount still can be tightened I think, but the muffler shield on top of the muffler directly below the carb is in the way making it REALLY difficult to access or pull the bolt; you can barely work a screwdriver in there to turn it and you have to bend the back edge of the shield down to do that. I think I need to use Locktite on both bolts though. I tried re-doing the Locktite on the top bolt and tightening the bottom one, and it held for all of about 5-10 minutes of running. After that I ended up bungee-cording the air cleaner to the engine to hold it against the engine block just to finish mowing, but by the time I was done both bolts were loose again. The carb mounts to the left side of the engine, btw. I can link you to a diagram if you like. (see below) I used the same tube of locktite I had from three years ago (still pretty liquid) but maybe it was no good? It was the removable type of Locktite and I am wondering if I should try something with a little more hold? Would JB Weld be better? I noticed it did grip the bolt in the hole better once it began to set but was afraid to tighten it down too much; just turned it till it felt like it was catching a bit and then let it set. Otherwise the bolt would just spin in the hole. I have gotten some more OEM bolts to try new ones but they are shorter than the bolt I used last; last time I just used an ordinary bolt that was a little longer than the original, and it did the trick, but this time I used the same longer bolt and it let go, after applying Locktite, tightening as best I could, and letting it cure 24 hrs before running. Should I replace the carb mount gasket again too? Seems to be ok but I haven't pulled it; I replaced it last go-around. The mower starts and runs just fine if I can just keep the darn carb on the engine! Here is the link showing the carb and air cleaner assembly for my B&S engine, no. 280707-0411-02. If you look at the carb bottom left, you can see the attachment point (intake??) you can also see the bracket I was referring to (no. 662 in the chart). Just a strip of metal that attaches to the little box with the choke linkage on it. Doesn't really support the carb-to-engine connection; the whole unit including aircleaner and bracket moves, I think. It's screwed down pretty tightly regardless. Carb and aircleaner assembly B & S 280707-0411-02 Thanks for any suggestions or advice!

The question was posed in 2009. It's now 2019. I expect most prolly everyone solved their problem by getting a new lawmower. But since you are here.... I have a hand-me-down Craftsman with a 16.5HP Kohler engine. After I changed the fuel filter the thing started stalling out on hills, etc. Same places. Same everything. It drove me nuts so I came to places like this for a clue. IF you are having the stalling problem after changing the filter...get the right filter. Heck, I went to a local mower shop to get the right filter and the owner refused to sell me one. Said I had the BEST filter already. Jeez. So I went elsewhere and got the right filter....same as the one I replaced and today...no problems. This is not all good bekez I had a new Cub Cadet all picked out. Dang! Listen...the right filter is on Amazon. So if you messed up like I did and got the one they said would work...the larger one...then go back to the smaller one: Kohler Engines 25 050 21-S Fuel Filter If you can't find it by the number...get one that looks like it and fits the Kohler. Just that simple. Good luck! My good deed for the day.

"using catch can, test for fuel flow to carb inlet by cranking engine. Be careful of fire." I would point out this will do no good as the engine has a fuel pump built into the carb. As mentioned way back up on this very old thread, check the vacuum impulse line from the engine block to the fuel pump. This will be the bottom line, gas line is on the side IF you took the fuel pump apart, did you find and properly replace the 2 tiny springs? I can send you a Service Manual for the engine IF you like. Address below, put in proper format and remind me the engine model number and what you want. Walt Conner wconner5 at frontier dot com

***"added benefit of not drowning the engine, if that IS what is happening."***"first the plug: The pictures were taken BEFORE running it at all, after it had sat from the night before"*** OK, so, "sat from the night before"??? Does that mean you parked the tractor immediately after running, while the engine was "hot from use"??? OR you had been trying unsuccessfully to get the engine started and running....prior to it having sat through the night??? This detail is quite important because: If you stopped the engine while "hot from use", there "should not" have been ANY wetness (unless from oil, but you say engine does not smoke) or "sheen" visible on the plug. The heat from use would have left the plug completely dry and any soot or carbon (from rich mix) would have been "dry and powdery". But, on the other hand, if you had been repeatedly cranking the engine (unproductively), and then just decided "to heck with this!!!! I'm done for today and I'll come back tomorrow"........and then next AM pulled the plug and photo'ed it, I'm afraid we still can't say for sure if your carb is "drowning" your engine, or if the wet condition of plug is simply from all the unproductive cranking. I'm thinking that "drowning" might already be taking place, and may be contributing to your present problem. One thing kssue should do at this point is to "pull" the oil dipstick and: (1)Smell the oil for the presence of gasoline. With so much unproductive cranking of the engine, plus the indicated "over rich" condition of the carb, even if the engine has not been "drowned", it certainly has been "flooded", and gasoline "might" be present in the fuel.(2) Do a "runny test". In the "old days", if a mechanic suspected gasoline contamination of the crankcase lube oil, he might perform a SWAG "runny test" by pulling the oil dipstick and then touch the wet end of the dipstick to one of his fingertip or palm callouses. Then he would observe how the oil "dispersed" from the central drop, into the swirls and whorls of the friction ridges in the skin. If the oil was thinned or contaminated with gasoline, he would see a relatively rapid spread of "color" into the network of tiny grooves that are the "trough" counterpart of the friction ridges of skin that comprise our "fingerprints". If the oil was not thinned, the drop of oil would tend to remain in the form of the single drop that was deposited on the hand. I no longer suggest that anyone perform the "runny test" in the manner of putting suspected oil on human skin. A similar test can be done using a piece of "unwaxed" or "unfinished" cardboard. This "plain ole cardboard" is the kind most packaging boxes are made of. All you need is a clean, dry piece of this cardboard. Using the oil dipstick, deposit one or two drops onto the cardboard. After the oil is put onto the cardboard, lay the cardboard on a flat surface, oily side up. Use a watch or other timekeeper to measure elapsed time. If the oil is very thinned (high gasoline content), the entire amount of oil will be absorbed into the cardboard in a matter of 3 minutes or less. The less gasoline in the oil, the slower the drop will be absorbed. Because there is no way to control all the possible variables of this test (moisture content of specific cardboard, type of cardboard, ambient temperature, etc.), it helps to also use an identical (or the same) piece of cardboard and test some other "oil samples" from different sources to compare the time it takes for the oil to absorb. Even that will be inconclusive unless the oil samples originally were the same product. But, if you use a couple drops of suspect oil, a couple drops from a different engine (believed to be ok), and a couple drops from a container of fresh, unused oil, you can get a pretty good idea. When I do this, I use a pencil to "graph" the growth of the "halo" that will spread outward from the center of the initial drop. Using the "timer", I mark the progress of the "halo formation" at one minute intervals. If you plan to test other sample for comparison, do them all in about the same hour using the same source of cardboard. Realistically speaking, the "runny test" is kinda "long and drawn out" for using to determine if oil is fit for service or not. It mainly serves as a way to get an indicator of gas in the oil AT THE TIME OF THE TEST only. In the case of the engine in this thread, I would probably be inclined to just say, "I don't know if I have gas in the oil, but with all that's been going on, there should be some gas in the oil. Therefore, I'm going to install the inline fuel shutoff valve and then change the oil for "peace of mind". ***"first the plug: The pictures were taken BEFORE running it at all, after it had sat from the night before"*** Oh, you mentioned "Have read of that under some other post as well but forget the circumstances...too many hours of sifting thru posts". In response to that, I am going to create a new thread to outline a "trick" I use a lot to "streamline" researching and saving found information. I'll probably come back to this thread and post a "cross link" to the new thread as well.