[Bibio]

dodgy battery or connection.

broken TPS.

split/disconnected hose somewhere.

dodgy connection block somewhere.

there is no easy answer to your question as there is far to many variables involved.

when you say it takes a while to get it to 'prime' again do you mean that the fuel pump is not kicking in or is it just hard to start?

but if it helps i seem to remember that someone else had the same problem a while ago and it turned out to be the TPS was knackered, i'm not saying that's the problem with your bike.