Thought i had ficed the fookin thing but seems not.
Was out a jaunt today and was running fine sitting in the On position then i filled it to the brim and started out and got the same issues as before, now i know what to look for i caught it i time before it cut out lol.
Ran it for a bit in RES and swtiched it back after 150km's and it was fine. Filled it again and yep you've guessed it started again.
Looka like i'm going to be busy tomorow taking things off and checking them.