Hi,
What's the problem? The fuel pumps on these are pretty rugged, but do need a good power supply to run. Check the electric feed and ground to the unit - if the pump's at fault replacing it should work, if not it could be poor quality fuel, or crud in the fuel tank. Is there an in line filter to renew? Presume you've eliminated everything else such as ignition system and carb problems. I had a brat with running problems - turned out that the fuel pump wasn't getting enough electrical power from corroded terminal to it!
