89 johnson 30 hp not runnig well when warm

[rossmartin]

I have this motor and it runs like a champ when its first cranked up, but after about 10 or 15 min it will still run great at slow speed but runs bad when its throttled up, it throttles up and then down up then down over and over, I dont know what could cause this, It is a brand new carb, but runs grat when cold so i dont think its that,
Model number is j30teced
there is no choke that i can see, but it does have a primer valve,
It does have a weak water pump that i am about to change but i think it is still getting enough water to keep it approiatly cool, Could changing the impeller fix my problem or is it something else?

 

[rossmartin]

Re: 89 johnson 30 hp not runnig well when warm

i got the water pump changed today and that seems to have fixed my problem, so if anyone else runs into the same issue try changing the water pump impeller.