Lawn Mower engine - loses power then regains power (tank, tanks, drain)
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First, I'm not sure exactly where I should post this, I thought gardening, could be automotive, but idk, please move this if it needs to.
I have a ~1997 Craftsman lawn tractor with a Kohler Command 15 engine. This season, I've noticed an odd problem developing, I seem to have good power for the first ~3-5 minutes of cutting, then I lose power for ~10 minutes, then it's running full power for the last 2/3 of my mowing. The loss of power symptoms seem to be low RPM, the RPM cycling but over all lower than where it should be, and an occasional backfire. It's oil is good, the air cleaner is used but still decent, the spark plug is fairly new, but I'll still probably check it and the gap.
I have a John Deere push mower that would do something similar, but I was never able to cut with it long enough to give it a chance to recover the power; even at low power the Craftsman has enough power to still cut the grass, the push mower doesn't. I bring it up to say that the solution there is to clean the carburetor as its particular carb seems to collect debris for some reason. I was thinking about doing the same to the Craftsman, I figure it can't hurt even if it's not the problem. But the closest I've found online to my problem is this: https://spaco.org/nopower.htm but it doesn't sound entirely right either since that site implies the low power was from the start whereas mine doesn't go low power until a few minutes of running. I'll also note that my startup procedure is to get the engine running, then get it out of the garage. Once it's out, I let it sit at medium speed for a few minutes to warm up first before starting to mow. Does anyone have any insight into this issue?
The ethanol blend gas has probably deteriorated the diaphragm in the carb- it's a very common problem.
Quite possible - even likely. Another thought is to drain the gas in the tank and carb completely and refill with no ethanol gas. Ethanol = dry gas, gathering water, but gasoline floats on that. The fuel line in a mower is from the bottom of the tank. Engine starts from the remaining gas in the carb, ethanol and water get drawn in, then the gasoline starts flowing.
I would guess a carb problem as well. In addition to no ethanol gas and checking the diaphragm try some Seafoam in the recommend amount to see if that helps degunk it.
My buddy has small engine repair shop and the amount of water coming out of those tanks is amazing. Better than 90% of the repairs he does are carb related.
There is gas station nearby me that sells non ethanol gas, it's about 80 cents more per gallon but if you are using any kind of small engine whether it's lawn mower, trimmer or even your boat motor it's worth the extra cost. For the two cycle I just buy the canned premixed gas, that is real expensive but I don't use much of it. Try and keep the tank filled for short term storage e.g. (1 week) and empty it for long term storage.
You can try this site to see if there is one near you.
My buddy has small engine repair shop and the amount of water coming out of those tanks is amazing. Better than 90% of the repairs he does are carb related.
There is gas station nearby me that sells non ethanol gas, it's about 80 cents more per gallon but if you are using any kind of small engine whether it's lawn mower, trimmer or even your boat motor it's worth the extra cost. For the two cycle I just buy the canned premixed gas, that is real expensive but I don't use much of it. Try and keep the tank filled for short term storage e.g. (1 week) and empty it for long term storage.
You can try this site to see if there is one near you.
Next time I fill up I can get the no-ethanol fuel and try it. I'm still thinking about cleaning the carb and maybe replacing the fuel filter, I don't think either have ever been done. Thanks for the information, I never would have thought the ethanol fuel to be an issue.
I am a good mechanic. I am a very handy and clever person. (I'm modest, too.) But small engine carburetors are my Achilles' heel; I have never, to the best of my recollection, successfully rebuilt one. (4BBL Holleys for high performance, no problem. 2-cycle weed trimmers, fuhgeddit.) Good luck.
I have a ~1997 Craftsman lawn tractor with a Kohler Command 15 engine.
Does it have a real (clutch operated) transmission?
If so, then buy a replacement engine and maybe a new deck assembly (rust etc) as well.
If not... replace the whole shebang with anything other than another Craftsman.
The ethanol blend gas has probably deteriorated the diaphragm in the carb- it's a very common problem.
Only one place near me has non-ethanol gas, and it's 93 octane and about $1.50 more per gallon than regular 10% ethanol, 87 octane. That didn't bother me since I don't use much in a season anyway, but a drawback is that they don't sell enough of it to keep the gas fresh. I bought what turned out to be old gasoline and it cost me an expensive repair bill (nothing was repaired, but the mechanic pointed out the old gas).
So non-ethanol is great and may solve the OP's problem, but only if it's fresh. Be careful. Another thing to check is that the air cleaner is clean.
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