Had trouble with one of ours would run fine until fuel tank half empty then no go, the problem was inside the fuel tank. After undoing the big plastic ring on top of fuel tank, you will be able to lift out about a five litre inner tank with a small hole(2-3mm) at the bottom that allows fuel in and subsequently to the fuel pick up. This hole was blocked. I needed to make a simple tool to undo the plastic ring, then needed to place ring in hot water to expand enough to replace it.
