hi mate

could be the cold start valve, i had a mk1 orion with a S2 lump, started perfectly without the valve, if u connected it however, it was flooding the engine. Another problem i had just recently on my mk3 cab (which is really starting to feck me off), was low fuel pressure. The easy way of telling whether the pressure is low, before u start it, whip the air filter off, and push the flap down, of theres fuel pressure it should have a bit of resistance, if not it will go down very easily and spring back up very quickly aswell.

hope this helps?

Andy