90 hp Evinrude losing power @ wot

[GlasV162]

Hi all,
I have a 1990 Evinrude 90 hp; newly-rebuilt powerhead and carburetors. Starts and runs fine, and idles well (about 900 rpm) and runs fine up to about 3500 rpm; after that it loses all power and will only run up to about 4500 rpm; then when slowing down, it won't idle back down; idle is stuck at about 1100 rpm. I'm afraid to shift back into gear at this high an rpm as I don't want to damage anything in the lower unit. I'm bringing the boat back to the shop tomorrow; this will be the 3rd time back to the shop since the rebuild and they still can't seem to diagnose the problem. Any suggestions?

 

[curtisimo1981]

Re: 90 hp Evinrude losing power @ wot

i had the similar problem on my 89 90hp johnson (basically same motor) it ended up being the throttle cable, for it not idling down. as far as loosing power is your primer bulb tight?

 

[GlasV162]

Re: 90 hp Evinrude losing power @ wot

What do you mean by a tight primer bulb? I assume this is something my mechanic would've checked.........but then again maybe not.

 

[Dennisanoka]

Re: 90 hp Evinrude losing power @ wot

May I ask the size of the prop that you are running?

 

[Dennisanoka]

Re: 90 hp Evinrude losing power @ wot

My next question will be what is the height of your engine on the transom/ what is the position of the cavitation plate in respect to the center line of the hull? Higher or lower and by how much? If it's too low and with the wrong prop 4500 is completely understandable. There may not be a single thing wrong with your engine except for the idle down issue which is a much smaller issue to address.

BTW I suggest doing all that you can to keep the mechanic your friend through this process he is still your best source to resolve this.

 

[GlasV162]

Re: 90 hp Evinrude losing power @ wot

I'm running a 13 1/4 X 17 pitch prop; cavitation plate is about an inch higher than the bottom of the boat, which I've been told is fine. When running great, I can get 5500-5600 rpm no problem. The last time it was in the shop my mechanic said it was a roller that had developed a flat spot; that was replaced, and it ran great for about 2 hours; then back to the same old thing of losing power at wot. Anyone know about this roller? Thanks.

 

[Dennisanoka]

Re: 90 hp Evinrude losing power @ wot

I would just ask him which one it was, otherwise it's just a guessing game.

 

[GlasV162]

Re: 90 hp Evinrude losing power @ wot

Does a faulty roller sound like a reasonable cause of this problem? I mean no disrespect to my mechanic, but this is the 3rd time back to the shop with the same problem--my boat has been in the shop more than in the water this year, so needless to say I'm becoming a bit skeptical. Thanks.

 

[GlasV162]

Re: 90 hp Evinrude losing power @ wot

Hello,

Well, I'm on trip # 4 to the mechanic. I called him today and he said it was a couple of fouled plugs. He offered to go to the lake with me and I accepted; we set a time for Friday; I told him I would pick the boat up today and try it and get back to him. Still runs poorly. I dropped the boat back at the shop tonight, called him and told him I would stop by at our agreed-upon time for a lake test. Now he says "Call first; I'm kinda booked up tomorrow." I'm trying to keep my cool here but this has gone too far. Any suggestions??