engine surging and vibrating

[rockins136]

Hello i have a 2003 johnson 115hp efi model j115pl4st tried cranking for first time this season engine started up fine but at approx. 3000 rpm it started surging and vibrating. I immediately went back to idle and checked and no water coming from indicator hole on backand i immediately switched off engine . It has never had water pump replaced i figure water pump needs replacing. would this cause the surging and vibration it idles fine.Any help appreciated.

[boats.net]

If it overheats it will go into safe mode and limit the rpm's.