geoff sydney,
1. The fuel line going to the carby needs to be taken off at the carby. The easiest way to do this is first push the fuel line towards the carby and then pull off.
2. Then turn the fuel tap on and have the end of the hose in a jar and check the fuel flow and you can also see if you have water in the fuel at the same time as the water will sit at the bottom of the jar.
3. If the fuel flow is good and you do not have water in the fuel then the next step is to take out the screw in the centre of the white plastic primer cap and see if you have any dirt in the screw.
4. If it has dirt in it then take off the cover
(be careful because a needle is in the cover) clean out the screw and the area where the fuel sits.
5. Then put the cover back on and make sure that the line on the cover is in a horizontal position to the carby as that is the setting for the fuel mix.
You can get more detailed information in the parts list and manuals area of this forum.