900 hart to start

My 2012 has been hard to start the last couple months. It sits a lot between rides because no time to ride. Once it’s warm it restarts better. I found that if you barley push the throttle pedal it seems to start easier. I put new plugs with no change. My thought is fuel pump but runs perfect when running?? My nephews 900 has the same exact issue.. Pulled plugs and cranked over with great spark
Any help would be great .