90 hp Johnson will only turn 3000 rpm under load until I press electric choke

[Mote]

Hi have 89 model 90 hp Johnson starts right up and trolls fine but when you go to WOT it will only turn 3000 rpm I pumped the primer bulb and it jumped 200 rpm then I hit the electric choke (and I am not sure how it works if it closed the butter fly or just sprays gas in carb I would think the latter the way it runs) and it immediately accelerated then I stopped applied WOT and held the choke in and it jumped through its *** and accelerated to 4800 rpm. So I am wonder it this is fuel restriction,fuel pump,or some common problem. I know nothing about this engine as I just purchased it started it on muffs (and of course it ran great at my home) any suggestions or prior experience would be great.

 

[pn]

Re: 90 hp Johnson will only turn 3000 rpm under load until I press electric choke

i'd just start from your fuel tank and end up at your carbs, piece by piece. sounds like a dirty main jet, or sticky needle inlet, or dirty filter, or old fuel burned off, or...you get my drift.

 

[emdsapmgr]

Re: 90 hp Johnson will only turn 3000 rpm under load until I press electric choke

Agree with pn. Engine is probably starving for fuel. You can do a simple fuel delivery test: Next time out, have a buddy constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If it runs ok, (or at least better) while constantly priming that hose bulb, it's a fuel delivery issue. Could be a weak fuel pump, or a hose, or a stuck anti-siphon valve, etc. Choking the engine injects extra fuel into the carbs.