1992 Johnson 15hp bog off idle

[Darren20]

I have a 1992 Johnson 15hp J15ELENM. I has developed a bog when tipping into the throttle. You have to play with the choke to get it off idle. I have rebuilt the carb, cleaned the screen at the pump, replaced the tank and hose. Replaced the roller for the throttle linkage.

It will run fine after running a while and getting it warmed up. Like running across the lake to fish. When we leave to come back we can run at an idle trolling or tip into the throttle and it is fine. It seems to be extremely cold blooded lately. We have owned it since it was new. Never was like this in the past.
Could a thermostat stuck open or shut be causing this. I really think it is temperature related.

Thoughts?

 

[timguy]

Right. Check operating temp with infrared gun. Only cost 20 bucks. I use mine for grease temp too when deep frying....lots of fun to own one. Should run 145 F. at thermostat area. If that doesn't do it try richening low speed needle. If low speed needle doesn't make much difference, then a port hole in area under welch plug may be restricted. Depending on how carb looked when it was cleaned, air pressure and carb spray alone may not open the blockage.