Very strange.Do these have a vehicle down/roll-over sensor?
That was my first thought, too because my raptor 700 has one. I'm still trying to find that answer but I have to wait until another day off. I work a weird schedule and the shifts are 12.5 hrs, then cook for the kids, homework, etc lol it's a long day on my work days. Weird how it'll do it on flat ground riding OR sitting still revving but does it worse uphill.
Wouldn't think anything electrically or mechanically would change on position but fuel demand will change with load and throttle position and fluid position will change with different angles. Wondering if it's fuel supply related...as in water in the tank...or pickup sock/filter blocked...or secondary filter issue if it has one. Think I'd run some pressure and flow rate tests..maybe drain the tank..pull the pump and check the filters...ect
I was off today and had some time to tinker and finally got a check engine code to flash! That helps narrow this down a lot. After hooking up my OBDii scanner i got P0261 which is cylinder 1 injector malfunction. So as of now I'm going for a dead or dying injector. During my tinkering it stopped firing up all together. Then I'd clear the code and fire it up, it'd run for 30 seconds or so and stumble out then die. That actually sounds more fuel pump related but I'm hoping the pump is fine and I can just clean or order a new injector and go with that. Either way, replacinging both would be right near 100 bucks which is A-okay with me.
Got a day off work and put 12v to the injector, added carb cleaner to the inlet, then 60psi of air. Mist only came out of 2/4 holes. Added 120psi air and mist came out of 4/4. EFI light problem fixed. Totally unrelated to the built up pressure, however, the canister is now deleted AND I removed 1 left and 1 right side front inner fender plastic for air flow AND I added a 12v dc waterproof fan and zip tied it to the frame right in front of the head aiming the airflow back towards the rear. This flow also goes across the bottom of the tank. Surely the combination of those 3 things will drastically reduce the under-tank heat and allow it to be pushed out of the rear. Time will tell. Thank you for sticking with me through this and offering your knowledge.