Pressure washer woes, should have bought a Kranzle!

My pressure washer(Clarke) keeps blowing the fuse in the plug but weirdly if I put in a new fuse, turn it on briefly it sounds as if it’s running ok but if I do the same with it connected to the water supply, it promptly dies. So it seems the electrics may be ok but something is wrong on the pump side, anything obvious I can check?