Update; This morning I undid the pump took it out and tried it directly connected to the battery and it worked.
I have put it back in and now running ok.
I think there may have been a bit of dirt or airlock in the pump and the varistream didin't like it.
If problem persists I may ditch the varistream and just use a switch as some do on here.
I will also be ordering a spare pump for any future problems.