89 evinrude 40hp running problem

"Looking for help... Recently

"Looking for help... Recently purchased 89 tracker pontoon stored in garage couple of years. Did basic stuff..plugs,fresh fuel,hoses,oil. Ran in test tank, seemed ok. Went to lake, motored out of no wake appr. 400yrd. throttled up, planed out,ran about.5ml.,rpm fell back[no tach on this model]and would not accelerate. No problem starting, idles good, no excessive smoke,compresion @140 both cyl.,operating temp.142 measured on cyl. head. Will only go est.2000-2500 rpm when problem occurs. Thanks for any help."

I'm pretty new at this but

I'm pretty new at this but have been doing some research on 2-cycle motors (trying to familiarize myself with).
I think your high Speed orifice might be clogged (?)
Regards and good luck!

"yea, sounds like a carb clean

"yea, sounds like a carb cleaning job."

"respectfully disagree. carb

"respectfully disagree. carb crud (varnish from evap'd fuel)usually shows up as poor idle and low speed performance as it partially clogs the much smaller idle and low speed jets 1st. motor should run fine at WOT even when it will refuse to idle.

what you're describing is fuel starvation after extended high fuel demand...ie, carb float bowls aren't refilling fast enough to keep up with demand. the diaphragms on fuel pumps, like all rubber in or on an engine or a vehicle, slowly turn from rubberish stuff to hard plastic and eventually to rock. when diaph doesn't move for long period (it works by flexing back and forth), this situation gets worse. rebuild your fuel pump 1st./ it's also easier to get at than the carbs."