Kohler Command Pro 18hp Leaving Me Stumped

[clean_cut]

I've got a command pro 18hp on a scag walk behind that's been working well for a few years, a while back it started to run rich, and then not at all, due to the plug being fowled so quickly. After cleaning the plug the mower runs alright for a few minutes until the plug gets fowled again and it begins to misfire and eventually quit running, here's what I've tried to fix it....

Checked airflow to carb
Replaced fuel filter
Switched spark plugs
Re-gapped spark plug (.020 in.)
Cleaned carb. MANY times
Installed a carb. kit that included a few gaskets, fuel inlet seat, and fuel inlet needle
Adjusted carb. (even at the leanest setting it still runs very rich)
Checked that the carb. float does float and isn't broken

It's been sitting in the garage for about 1/2 a year now, I just can't figure out what's wrong with it, do I need a whole new carb ($130-150ish)?

The carbon on the plug seems to be a dry powdery carbon, not oily.

The exhaust also seems strange, it has a chemical smell/fume to it, that seems to burn your nose, maybe the engine's always ran like that though.

Anybody got any ideas on what the issue could be or how to fix it?

[Restrorob]

Originally Posted by clean_cut

Installed a carb. kit that included a few gaskets, fuel inlet seat, and fuel inlet needle

There's a right way and a wrong way to install the seat, Which way did you install ?

I see no mention of cleaning the fuel tank ?

[clean_cut]

Originally Posted by Restrorob

There's a right way and a wrong way to install the seat, Which way did you install ?

I see no mention of cleaning the fuel tank ?

Well to install the seat, I got out a hammer... just kidding, I used the tool given in the kit to get it seated at the right height, following the given instructions, so it should be installed correctly.

I never cleaned the fuel tank, but I have drained it and put fresh gas in there, I forgot to mention that.

[Restrorob]

Originally Posted by clean_cut

I used the tool given in the kit to get it seated at the right height,

Tool in the kit ? Was this a "Kohler" kit ?

Just need to verify you got the seat in properly.....

[clean_cut]

http://www.ebay.com/itm/120753124041...ht_4980wt_1037

Thanks the link to the ebay page, the "tool" just was a device to measure the depth of the inlet seat I believe.

[piston slapper]

Is the Command a single or twin cylinder? (Need model and spec#)
Havent seen any command twins with serviceable seats. Whats up with the .020 sparkplug gap?

[clean_cut]

The engine is a single cylinder model # cv493t and spec # 27513, yeah, I just checked the manual and it states states that the spark plug should have a .030 in. gap... oops, I guess I just had .020 stuck in my head for some reason and didn't even think to check the manual when I adjusted it. The spark plug gap might be part of the problem but I still can't figure out why it's running so rich.