I have a 52" Scag turf tiger commercial mower with a 23Hp Kaw engine liquid cooled. It has an intermitent starting problem that no one can find the problem. You turn the key and nothing happens other than you can hear the electric fuel pump run. The PTO will engage when the key is in the on position. Other than that it still will not start, turn over, click or anything. Once it decides to start it's fine for days and then it happens again. I have had mechanics look at it as well. I have even taken directly to a mechanic when this happens and yes of course it then starts for him. Please help.