Thanks for the replies gentlemen.
Colin - The tank was rinsed out, but not resealed, which (with hindsight) may have been an error.
Mike - I will have a looks at the fuel line from the tank when I get the chance.
Wharfdale - Due you have any more details about your extra pump?
( Like where is located, how is it wired up, etc. )
Cheers, Paul.