Skid, you are really over the limit trying to weld 5mm to 9mm with a Clarke 90. See here for an interesting review of the 90EN:
http://www.mig-welding.co.uk/clarke-90.htm
http://www.mig-welding.co.uk/clarke-90.htm
This is a worry, I've got braided fuel lines running inside the car. There is a constant fuel smell in the car which is just part and parcel of running braided lines. I shall rethink!!