Inherited a 20+ year old tiller from a friend. 6.5hp engine is tired. has leak in gas tank on bottom. wants to start and then immediately stops. figure the carb definitely needs cleaned and/or replaced..is it possible the tank leaking allows air into the system? should the tank cap be vented? doesnt appear to be. someone also added a fuel shut off and inline fuel filter..will replace those as well..gas line from tank to carb looks longer now after these additions. could that affect gas getting to carb? thanks for any help..don