Thanks for your help, JR. Just posted an update above. We bypassed the carbon canister and the problem no longer adds up to a tank vacuum issue. Seems to be tied to heat as problem only happens after some time riding. Is it possible for the fuel pump to overheat? But then why would it work again immediately by cycling the ignition? The behavior makes it seem like there is a sensor or breaker that flips when the pump reaches a certain temperature and turning the key off and on again resets that sensor or breaker until it overheats again a minute later.
Please keep the ideas coming... We're heading for the Chinese border in a couple days and are hoping to have some fix or workaround until we reach India, where our visa schedule is more flexible for proper fixing.
Originally Posted by JRWooden
The other thread is a good one.
I suggest you hold a strip of paper near the fuel tank cap when you open it next time and as the pressure/vacuum is released the paper will deflect in or out ..........
If it is deflecting IN (vacuum) then it may be the case that the vacuum gets so high the fuel pump can not overcome it.
This would likely be the result of a clogged charcoal canister (assuming this is a USA built bike) or perhaps the check valve in the vent line from the tank.
I carry an extra "straw" from a can of WD-40 in my tool kit so that I can close the gas tank lid on it if needed and hopefully maintain venting until I can fix the real problem (if it is a venting issue)
What is the latest news?