When I took the tank off my bike over the winter I used a piece of tape to mark which fuel line went into which tube. The tape fell off at some point and when I went to put the tank back on I wasn't sure which line goes to which tube under the tank. Each line has a plastic ring on it marked with a letter. One has the letter 'R' (I'm guessing for 'Return') and the other has the letter 'M" (not sure what this stands for).
I already tried hooking it up and the fuel pump comes on, the bike turns over but doesn't fire up. I'm guessing I got the hoses mixed up and I just need to swap them but did I do any damage by getting it wrong?
M stands for mandata or delivery. R does stand for return.
You didn't do any harm most likely as the pump still got fuel in it.
Switch them and give it a shot.