I thought the area around the fuses could be the issue so purchased one of those new spade fuse blocks, it does seem to manage the current better. But the relay and cables still get hot with just a few minutes of use.
I would say too that the pump shouldn't draw that much current and with testing it is certainly from this cable onwards is where the draw is coming from, as once disconnected and only the tank pump in place every thing goes down to just 1.5a.
I'll have to take the main pump out again and as you say replace the crimp connectors and check for shorts :-).
Thank you for replaying Daniel.
