1990 Evinrude 9.9hp - Won't rev up

[DeanHensler]

I'm looking at buying a 1990 Evinrude 9.9hp engine. The guy who is selling it says it won't rev up. It will start just fine and idle fine, but when you try and throttle up it just kinda sits there and bogs down. He says it needs a new throttle cam. He isn't willing to fix it because he doesn't have the tools to remove the flywheel or the time to do it. He's selling it for $400. This model has an electric starter on it.

Does this sound like a throttle cam issue? How hard is that to replace? I'm pretty mechanical and I've built automobile engines before, but I've never tinkered with an outboard boat engine.

Should I stay away from this thing or risk $400 for a motor that might only need a minor repair?

Thanks!

 

[boobie]

Re: 1990 Evinrude 9.9hp - Won't rev up

Never believe a seller. The mtr could have anything from bad ignition to a blown piston. The only way you can find out is to check it out yourself. $400 sounds a little high.

 

[tazrig]

Re: 1990 Evinrude 9.9hp - Won't rev up

Never believe a seller. The mtr could have anything from bad ignition to a blown piston. The only way you can find out is to check it out yourself. $400 sounds a little high.

I'd say a lot high for an unknown problem such as that, and I'm with boobie "never believe a seller". (unfortunately) :blue:

 

[DeanHensler]

Re: 1990 Evinrude 9.9hp - Won't rev up

What exactly does the throttle cam do?

 

[AlTn]

Re: 1990 Evinrude 9.9hp - Won't rev up

it synchronizes the timing advance with the throttle valve <butterfly> opening...look under the sticky Top Secret Files to get some info on evaluating an outboard, ie.; compression test, checking the lower unit, leaks of exhaust gases, signs of the motor having been over heated, bearing noises,etc...also google..leeroy's ramblings 9.9/15 hp. johnson/evinrude maintenance and repair...in my opinion, $400 for an electric start, 9.9 hp. FRESHWATER only model is reasonable depending on the condition....as always, it pays to know what you're looking at....the UFI ignition system used on that series of motors is a weakness you need to be aware of

 

[DeanHensler]

Re: 1990 Evinrude 9.9hp - Won't rev up

Okay so I went and looked at this motor today. The seller didn't have the electronics hooked up so I couldn't see it run. I told him I wanted to see it run and do a compression test before buying it. He agreed to get the electronics hooked up in a couple days and I'll go back.

In the meantime I had him show me the broken throttle cam and I took some pictures. Please take a look and let me know if this in fact the throttle cam. I am curious how difficult this is to change. He said he would do it for $100, making the purchase price $500. He said you have to remove the flywheel to replace it and he didn't really want to mess with it.

Feedback appreciated!



Also, what year is this motor?

 

[the machinist]

Re: 1990 Evinrude 9.9hp - Won't rev up

That is a plastic plate that is just bolted onto the timing plate. Very reasonable replacement cost.

What will happen is as the motor is increasing speed as the throttle/timing plate is advancing (and this broken cam being attached to it) when the carb roller drops off the end of this broken cam, it lowers the RPM because the roller is now in the same position as if it was ildling. And it is then hard to retard the throttle twist grip because the cam roller may not want to climb back off this broken edge. Simple fix. Pull the flywheel, electronics & timing plate, replace the plastic cam & you are good to go.

Likely the reason it broke was he was trying to adjust it by the adjustment screw at where the break is & went too far, breaking off the outer 1 1/2" AND the screw.

If the compression is good, you may be getting a sleaper. However don't let him know what you have found out, play dumb.

From the model number, it looks like it is a 1992 Electric start, Extra long Shaft 25" Sailmaster unless someone has changed the shaft length.

Good motor, actually one of the best as it is the last & most improved version until they went to the plastic cowling model in 1993.