Honda H5518 won't stay running

I found that the fuel cutout solenoid was not working, so I replaced it. Now when I turn the key to start, it runs but stops as soon as I release the key. This is a Honda Tractor H5518A  S/N RZBC-1101444A. I now am suspecting the Combination Relay  which is an Omeron G8D-133H. I didn't want to replace it unless I can get verification that that is the problem. As the relay is quite expensive.