Craftsman Kohler Fuel Filter Problem: Solved
I'm posting this as an informational message for those who have problems with fuel flow in Craftsman lawn tractors with Kohler engines (possibly this affects others as well), specifically after changing the fuel filter. My model is a 917.272481 Craftsman LTX1000 with a Kohler Pro 18HP engine (Model:CV492S Spec:27506) bought in 2002. Note that this engine does not use a fuel pump and relies on the gas tank being higher than the carburetor so that gravity carries the gas to it.
In 2004 I bought a replacement fuel filter for this tractor based on the model number listed in my manual, 25-050-03 which today maps to new Kohler part number 25-050-22. This filter was an aftermarket that mapped to this same part number and was clear rather than a white opaque plastic. After doing this I had the problem that many in this forum have posted about where the filter appeared to run out of gas and the engine would stall after about 20-30 minutes. If left to set, the fuel would eventually fill back up. The original filter could be put back and this problem went away which pointed to the new fuel filter as being the problem.
I ended up using the old filter since they really don't see much action on a lawn tractor, but this season I decided to find a proper replacement. After some research in the Kohler manuals and having a part shop look up the filter type based on engine model number vs. the part listed in my manual I discovered that Craftsman made a typo in their documentation. The part number 25-050-22 (or 25-050-03) is a 50 micron filter designed for a fuel pump where they also make a 25-050-21 (or 25-050-07) which is a 75 micron filter designed for a gravity feed system like my engine is.
Kohler isn't particular to brand of filter as some would suggest in these forums but rather it is particular to the micron size (and thus flow rate) of the filter media based on whether you have a fuel pump providing extra pressure or just have lower pressure gravity carrying the fuel directly to the carburetor.
So if you can trace your fuel hose as going straight from the gas tank and into the carburetor float bowl, use the filter 25-050-21 with the bigger 75 micron holes and if you have a fuel pump in between, then use the 25-050-22 with the 50 micron holes to keep your gas cleaner. Using a different brand should make no difference on a Kohler as long as you can determine which micron size it has (these branded maintenance parts are just sourced from some other company for cheap and then marked up). I would avoid anything that says universal without specification though since you have no idea what they decided is a universal micron size.
Cleaning the carb never hurts either but that's a different thread.