Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

[Case450]

when i get up around half throttle the motor putters out and dies.
if i kinda fight with it i can get it to keep going for a bit as soon as i throttle down and it gets around half throttle again it dies. starts and idles perfect.

i'm trying to get fishing but this is holding me up. ideas? suggestions? i'm new to outboards but not to turning wrenches so i'm game for anything!

thanks!

 

[will941s]

Re: Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

You may need to take your carb apart and clean your highspeed jet. Your highspeed jet is mounted inside the bottom of your float bowl. When you are at idle the fuel is passing through your idle speed jet (which is the adjustment on the front of the carb) and when you give it the gas the flow is diverted through the highspeed jet in the bottom of the bowl. The highspeed jet may be clogged and causing it to starve at mid to full rpm's. Let us know what happens.

 

[Case450]

Re: Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

awesome! okay i'll check that out tomorrow....i was thinking it might be something to do with the fuel delivery...will keep you posted! thanks a million!

 

[Mi duckdown]

Re: Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

How old is your gas? Water in Gas? Always start with basics. I had water in my tank. forgot to drain the fuel line from the tank. What a mistake.

 

[Case450]

Re: Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

yeah i put fresh gas in and some sta-bil additive to try and clean it out some. i haven't time to tinker with it this evening. will keep you posted when i get it figured out.

 

[Case450]

Re: Mid 80's 25hp merc tiller 2 stroke dies when i get around half throttle

I've changed the coils, plugs, wires, filter screen, i've also put in fresh gas mixed at 50:1 with a tiny bit of sta-bil in it. I put the muffs on it and she started right up and idles fine...i revved it up some and no problems so i dropped her in the water and took her for a spin. First pass down the lake i went at wot and i was pleased. First because i made it to wot and because the boat handles like a champ! lol
After my second pass the motor started sputtering again when coming into half throttle from either idle or wot. I cruised by the dock around half throttle and when i throttled down to turn around it stalled...i fired her right back up and limped back to the dock. After i let her sit for about 2 minutes i started it again and she idled for almost 10 minutes then i ripped off again at wot (again fighting slightly to get there) and back i come...again fighting the half throttle demon when powering down to land the boat.

I want to investigate this high speed jet but am unsure how to do it. Would it be possible to get a walk-thru?
Thanks guys!