Yamaha 3 hp runs 3100 rpm at full throttle

[Zlaninomma]

I took this outboard to the lake on a 11 ft zodiac. It will start fine, runs at 1250 rpm idle and 950 in idle when gear engaged. It will push the inflatable to 5 mph with one person. Engine runs smooth. But there is no difference in rpm when 50 or 100 % throttle. Rpm shows 3100 at 50 or 100. Outboard is 2001 Yamaha 3 hp. What could be wrong here? Or is that it for 3 hp engine. I think range is 4500 to 5000 rpm at full