Gamefisher 9.9 help please

All,

I need your help. I have a 1989 Sears Gamefisher 9.9 outboard. This was my first outboard and I rebuilt the carb, replaced the impeller, and did a lot of work on the starter. She starts great now and runs smooth in low RPMs but I have a very strange problem. When I twist the tiller to full throttle she doesn't often go into full RPMs. Instead she perks up to 6-7 miles per hour and then several minutes later all of a sudden full RPMs kicks in and she's going 10 miles per hour. She always maintains full RPMs once she hits it but the moment I lower the RPM and try to go back...she's back to the lower RPMs. I'm typically going in a straight line when this happens and it's frustrating not hitting full RPMs all the time. Any ideas what it could be? I've installed new fuel lines, a fuel filter, and re cleaned the carb several times now. Any help would be appreciated as I'd love to fix this very annoying problem.

What size is the boat that your motor is on?? When it is going at "lower RPM" is it planing? I think that you may be just at the point that you don't have enough horsepower to get up on plane. When the motor gets to high RPM do you find the bow of your boat lowering down at the same time?

It takes a significant amount of power to get your boat on plane and as soon as it does, the power required to keep it on plane is much lower. You might be puttering at the maximum displacement speed until you find just the right conditions to get the boat on plane. That would explain why it runs fine once it's at speed, as well as why it goes right back to the same condition when you reduce the throttle.

An easy way to test this is to see if you can remove any significant weight from the boat. Take out any trolling battery, and other heavy items. If it takes less effort to get to the high rpm's this might be the issue.

If this is your issue, the two ways to fix it are: more horse power (either through incremental adjustments or a bigger motor), or lighter load.

Good luck!

Wow, I never thought it could be that. My boat is a 14 foot Sears Gamefisher Mod v. She's rather for 25 hp and I typically take her out with my best friend...close but not quite fully loaded. To be honest, I don't think we have ever planed and I plan to upgrade to a older Mercury 25 hp 2 stroke but I put so much work and effort into the 9.9...I want to see her come back to life and work flawlessly. I'll try taking my boat out solo next time and see if that was it. Great advice.

Out of curiosity, anyone have any other ideas? Thank you very much.

Actually, if I may add...I don't think it's the planing. It could be and to test that I'll need to try taking my boat out solo but the reason I don't think that's it is because I upgraded the reed plate, the exhaust, and carb in my 9.9 to convert it into a 15 HP outboard (really fin project). It now can reach 12-13 MPH but is still not hitting full RPMs. I also am not convinced my boat has planed yet but shifting weight in my boat could help out there.

My original thoughts were something was in the fuel system but I've run Seafoam through it thoroughly, replaced all fuel lines and the fuel line filter, and I still have the issue. Fuel is good too...plus it's treated for ethanol and has a stabilizer in it.

Throttle isn't the problem either as I am giving it full throttle both with the low and high rpms. Any advice/help would be appreciated. I would love to get my motor running really well before making the 25 HP upgrade...if nothing else...so I feel I conquered my 9.9 rebuild and I know something. Thank you.

Have a look at the throttle linkage with the cover off. See if it is moving properly advancing the spark and the carburetor together. Check for binding or sticking. Typically older engines need all the working surfaces serviced. Everything should be clean and lubed right from the twist grip to the ignition plate. If something is hanging up, that could do it.

I can't take a photo with the cover off right now...deployed until July

But what I can tell you, having worked on the engine and taking it apart multiple times...the throttle advances the carb and throttle plate together with no issues. I've played with it many times and when it goes full throttle, it has fully advanced the throttle plate which in turn pushed the carb lever all the way down. Sorry for possibly getting the terms wrong. I just not, mechanically it appears to work fine. I'm hoping perhaps the planing is the issue but honestly...if it's happening when it was going 5-6 mph and not it is when going 10-12 mph...I don't think it's planing. I hope that helps.

I am guessing this isn't a common problem then? I was hoping it was a simple fix or more easily understood. I am guessing older outboards are never that easy...lol. Part of the love/hate relationship with them.

Not to push the topic too much, but if you aren't planing, you would never get above 6 mph. There is a very hard limit of how fast a boat can go in the water without planing. Look up some information on Displacement Hull Speed vs hull size.

If you really are pushing 15 hp on a 14' boat, then it certainly isn't a HP/planing issue, as you should have plenty of oomph to get that boat going.

Have you adjusted the points at any point in time in the past? If your timing isn't right, you could see a loss of power in a similar way.

I had two gamefisher / force 15hp motors that I got for cheap because of issues. The things I found were that one of the motors had a broken key between the flywheel and the crankshaft, preventing the motor from running. And the second thing I found was a point cam that was upside down, causing severe timing issues. For the timing cam issue, the motor would run under open throttle, but wouldn't idle. Not sure if you've been fiddling under the flywheel or not, but timing might be an answer.

I just saw your other post about a V-Hull recommendation. 3 people with full gear on a 14ft boat, even with 15 hp may have problems planing. My brother has a 14' with a nice 15hp Suzuki 4 stroke on it. With him, me and two small kids, we couldn't keep the boat on plane with small waves around us. Try the simple things first, and a quick run with no weight in the boat wouldn't cost you anything.

Good luck!

@kofkorn, than you for your insightful advice. I didn't realize if I was above 6 mph I'd be planing. This is my first boat and I took her out about 6-8 times last year. Boating was quickly become a passion of mine and I just assumed we haven't planed yet.

And yes, I've worked extensively under the flywheel. My engine originally wouldn't start so I replaced pretty much everything under the flywheel. New contact points, saturators, and capacitors. I installed all according to the owners manual including the appropriate gaps on the contact points when the flywheel is in the correct position. I can always pop off the flywheel again to double check.

Mainly reason I am talking about the RPM issue is because I can notice a big different in the sound og my engine which I assume are the RPMs. The engine sounds like it's working a lot less hard at full throttle which is why I assume I'm not at full RPMs. Perhaps I have it all wrong and everything is going right...and it's just a different sound and less strain on my motor once I plane. The 15 HP gets me up to 12.5-13 mph with two people. I was hoping for slower to 15 mph since my 9.9 could hit 10 mph but honestly...I am just going to go out and fish...and rebuild my 25 HP Mercury to be my primary power.

Thank you everyone for your time and advice.

claytonb78 said:

Actually, if I may add...I don't think it's the planing. It could be and to test that I'll need to try taking my boat out solo but the reason I don't think that's it is because I upgraded the reed plate, the exhaust, and carb in my 9.9 to convert it into a 15 HP outboard (really fin project). It now can reach 12-13 MPH but is still not hitting full RPMs. I also am not convinced my boat has planed yet but shifting weight in my boat could help out there.

My original thoughts were something was in the fuel system but I've run Seafoam through it thoroughly, replaced all fuel lines and the fuel line filter, and I still have the issue. Fuel is good too...plus it's treated for ethanol and has a stabilizer in it.

Throttle isn't the problem either as I am giving it full throttle both with the low and high rpms. Any advice/help would be appreciated. I would love to get my motor running really well before making the 25 HP upgrade...if nothing else...so I feel I conquered my 9.9 rebuild and I know something. Thank you.

Click to expand...

Would you be willing to share how you went about doing this conversion? I'm thinking of doing the same to my '94 over the winter and any help would be greatly appreciated.

It's been many years but I believe I swapped out only two parts. I bought the 15 HP carb and changed out the exhaust nozzle. While I don't think I ever got the motor fully running smoothly, it was a noticable increase in performance with the 15 HP carb and exhaust. BTW, if I recall all I did was compare the parts of the 9.9 HP to the 15 HP to identify what parts were different. 99% of the two motors are identical.