Johnson 40 HP Motor Will Not Run to Speed

[Guelfog]

have a Bass Tracker with a 40 HP Johnson Motor J40ELCD. The Motor will not run over 2000 RPM with Full Throttle(10 MPH?). I can get the Boat up to 30 MPH(3500 RPM) if I hold the Primer Switch in. If I let the Switch out the Motor immediately slows down. Can someone tell me What is wrong. I have checked for gas leaks and see none. I have even changed the gas primer bulb and hose.

 

[rodbolt]

Re: Johnson 40 HP Motor Will Not Run to Speed

Hello<br /> if it will speed up when you push the primer the carbs are not flowing adequate fuel for some reason. usually trash or water. do a compression test to rule out any mechanical damage caused by a possible lean fuel condition then rebuild the carbs and retest. if you have the small diamond shape pump look under the strainer cap to see if you have the one with small orange rubber check valves . these valves failed a lot and can work their way to the carbs.<br /> good luck and keep posting