I have a 74 evinrude 70 hp .that is hard to start even after its warmed up.i have to use the idle control lever every time. after it revs up it will idle fine and it runs good. but i can drive around for a while and shut it off and it wont start back up unless i use the idle control arm. i tried setting the idle up a little but it did not help. what do i need to do to just turn the key to start my boat?