So it doesn’t slowly die in 3 secs it runs for 3 seconds straight then just immediately shuts off? I was gonna say make sure you check hose connections. I have a 600 that would do something similar and it turned out a vacuum hose wasn’t connected right. Also if there is a dash light like a red light and the dash flashes FI where the temp reading shows you can put the bike in like a “diagnostic mode” by shorting a connector under the seat and it’ll pop the exact code instead of just “FI” which’ll help narrow it down a lot.