my mates tg10, with the standard grey head motor, is playing up. it starts fine, but refuses to keep running unless i keep tapping over the exhaust tip. like it cant suck fuel thru by itself. ive gone thru everything on the motor for airleaks and breakages. i'm at a loss now. it has good compression, starts easily, glow plug is good, mixture is good, it must be impossible for there to be an airleak too. any tips would be great.

Replace the fuel tubing and check the tank and fuel filter.