Kohler Model and Serial Number

I purchased a used 1995 Simplicity Sunstar with a 20 hp Kohler engine. It starts and runs fine until it gets about 45 minutes running time on it, and then it starts to sputter and just dies. I have been down this road with another kohler twin (16 hp) last year. I replaced the fuel pump first then the ignition coil and that cured the the same problem. I want to replace both parts again, but the model and serial number on the engine were put there with a plastic decal and fuel line rubbed thru all three of the numbers. The fuel pump should be easy to find , but I still would like to know if there is a model, spec, and serial number somewhere else on this engine to confirm, for the coil and other parts I may need.
(this Kohler has an oil filter too. ) Some of them made this year apparently do not.)

 

I went to kohler website and all I could find close was a magnum M20 with a simplicity tag on it. This magnum had a fuel pump on it that was threaded and did not look like the one I have. Mine is a pulse type pump, is square, and has 3 tubes on it for hoses. It mounts right on top of the engine, and does not have an arm that rests on the camshaft like the one in the photo That makes me wonder about the module I need too.

 

This engine is a CH20S - 64512 twin cylinder Found the parts, if I need them.

 

That is a model for a horizontal shaft engine... is that what you have?

Have you tried loosening the gas cap when it acts up to see if it does better?