Odd fuel delivery problem, clues provided...

[boman]

Go for a ride with the fuel cap open. My Bandits cap was not venting at all, and my symptoms sound very similar. Once I had worked out the problem, I rode home from work with the cap open and had no issues. Found a small vent hole in cap blocked off. Done 5000 + kms since then and no issues at all.

hope this helps?????

[idb]

I reckon that's what it sounds like too.

[Pixie]

More the air above the petrol expanding, which should be expelled through the vent. But either way, any increased pressure in the tank won't prevent the flow of fuel - it will assist it.

Over pressure can overcome the float needle valves and raise the float level.
This can cause the engine to die from being too rich