1997 Evinrude 9.9, Loss of Power after about half throttle.

[Akfish42]

I just acquired this motor. It was recently found in a garage, and appears to be near new. The original spark plugs hadn't even ever been removed. The motor is spotless, not a scratch on the skeg or prop. I was able to tank test it from the guy I bought it from and it seemed fine, although I only started it and ran it up to about half throttle.

I took it out today and it starts and runs pretty well up to about half throttle. Any higher than half throttle and the motor begins running poorly, sputters, will rev up and down from half to maybe about 3/4 power. I have brand new gas tank, and hoses. The bulb stays hard. The plugs seem fine, not fouled or wet. I backed out and tried various positions on the accessible carburetor adjustment screw, with no change, except I got it to idle a bit better. The carb is secure.

I'd like to know what sequence I should go through for troubleshooting this? I have very limited tools at the moment. My family is arriving here in 10 days and I need to get this fixed before they arrive! My funds are minimal so taking it to a mechanic is a last resort.

Right now I'm going to the store to get some carb cleaner and canned air. I'll pull the carb and clean what I can and make sure the float works and so on.

Any help is so very appreciated!

Thanks
Akfish42

[78 mckee]

Disassembling the carb and cleaning is the first step.

[USMCTC]

You may try replacing the fuel filter first. with a dirty filter the motor will idle and run at slower speeds just fine, then when you increase the throttle the debris will clog up and cause the carb to not get enough fuel and sputter. I see this happen quite often.

[Akfish42]

Hmmmm, I did check the screen on the fuel pump. I don't think there is any other fuel filter? Should I pull the fuel pump off and disassemble for cleaning?

Thanks

[kbait]

If the pump is working, I wouldn't disassemble it. Bring a squirt bottle of premixed fuel with you next trip and squirt a little in the carb when it fails. If it gets worse, you're having a flooding condition, if it get's better, it's likely a blockage in the carb. If it is a flooding condition, perhaps you have a small tear in the fuel pump diaphram and fuel is dumping directly into the cylinder that it draws it's pulse from, effectively flooding out that cylinder. You can test by pulling the 2 mounting bolts from the fuel pump and pull the pump off it's mounting gasket, leaving the hoses connected. You need to find 2 nuts to then put on the mounting bolts and cinch them to the pump itself so the pump is now isolated, and all bolted together like when it's mounted. squeeze the fuel bulb and see if any fuel comes out of the 'pulse' hole in the back of the pump. If there is, you have a bad pump diaphram. Good luck!

[kbait]

Also, be certain you have the correct spark plugs and they're gapped at .030".. and the plug wires aren't cut/damaged.

[Akfish42]

Thanks, I'll check this after I get the carb back on. I just got it off, had to grind down an open ended wrench to get to the inside mounting nut (major pain). The carb looks like the rest of the motor, pristine. I'm going to pull the bowl and look at what is listed as high speed orifice, i'm hoping there is an obstruction there. Thanks again!

[aeigenman]

On my '88 evinrude 150, I had a similar problem. Mine has a mechanical linkage that changes engine timing with throttle position. There is an arm under the flywheel that can slide back and forth about an inch. The throttle position has a small mechanical linkage rod that ties to this timing arm. The connection is a little piece of plastic that clips on and does nothing more than tie the rod end to the timing arm. This little piece of plastic cost me some rediculous amount of like 50 cents, but cost me an hour of time and stress trying to limp my boat back to the dock from the middle of the lake. I found it through luck, it was not immediately apparent to me what the problem was. Not sure if your motor has the same type of set-up, but if so, hope this helps!

Aaron

[Akfish42]

Hey Aaron, yeah my motor has the same set up. Mine seems fine as I have removed and installed it twice now. I just put the carb back together, it was literally pristine, not a smudge of anything on or in it. I really don't think this motor has been used much or at all. I also checked the fuel pump, as per "kbaits" guidance, and it seems to be fine. The one thing I did find was that the fuel line going to the fuel pump was a bit too long and was somewhat kinked where it made a bend, so I shortened it to remove the tight bend. Could that actually be the problem? Holy Mokus I hope so! I'm off to the river for a test run!

[Akfish42]

I tried you suggestions, the fuel pump seems fine, the carburetor is clean as a whistle, I took off the air box and sprayed gas with little effect, except to bog the motor down if i sprayed in too much. The plugs are like new correct type and gap. What next? I'm thinking it must be an electrical gremlin?

Thanks

[iwombat]

Even if the carb looks clean, all it takes is a tiny bit of crud in a jet to make it behave like that. Get a kit and do a full rebuild. Remove, soak and blow out all the jets.

[the machinist]

Are both spark plugs firing? It could very well be that you are only running on one cylinder.

[Akfish42]

Thanks iwombat, I have a kit on the way. So my spraying fuel into the carb with no result was not an indicator that the problem is not fuel related? I believe the only needle valve on this carb is on the top plastic part. I'm assuming I should not clean the plastic part with carb cleaner? If the kit comes with a friction plug will I be able to remove the vertical brass tube for thorough cleaning?

Thanks machinist, It is firing on both cylinders. It will fire right up and idle beautifully with either plug wire removed! I can see how this could easily be missed.

I really appreciate the help here. Thank you!

[AlTn]

Ak...can you post a model no.?...2 stroke?..4 stroke?...I've looked at diagrams at ********** and at shop.evinrude.com...hard to tell what links the throttle plate opening to the timing advance <link/sync>...I agree with you and would use only hot/soapy water on that plastic upper..be wary of removong that brass tube , I'd suggest you clean it in place....often times a small air leak at one of the fuel line connections can cause that "fluctuation" of rpms with throttle increase..does pumping the primer blub from the tank to the motor help when the motor is doing this above 1/2 throttle?

[Akfish42]

Thanks ALTn it is model # E10REUS a 2 stroke. This motor is like new.

It appears to me that the timing advance is turned directly (as a whole unit under the flywheel) by the throttle linkage which in turn operates the carb throttle opening via a wedged shaped piece of plastic linked to a plastic roller on the carb linkage. If that makes any sense! My terminology isn't up to par.

I'm almost certain there are no air leaks. Pumping does absolutely nothing. I tore the carburetor apart and cleaned it with carb cleaner (metal parts) soaking for about 3 hours, poked out all orifices with thin strand copper wire and blew everything out with air. Yesterday I tried squirting a little gas in the carb throat while above 1/2 throttle with no response either, which is making me think it may not be a fuel issue.

I do have the carb soaking again as we speak, this time I'll let it soak for 24 hours. After this I guess I start "throwing parts" at it!

Thanks

[AlTn]

ok...in my limited experience...somewhere on that plastic piece < throttle control cam> which is attached to the armature plate there should be a mark of some kind. The roller on the carb linkage should be on this mark just as the throttle plate in the carb throat begins to open...this is to occur with the throttle handle in the start position. When the throttle is as far as it'll go, the roller should be near the end of the cam <full timing advance> and the throttle plate should be horizontal in the carb throat. We just advance the throttle grip as far as it'll go with the motor in neutral <the interlock will prevent it from going too far>, pull on the choke, and pull the rope..usually starts on third pull..1978 9.9 Evinrude. You'll need to reduce the rpm's before shifting.

[Akfish42]

Ok, thanks ALTn, but it starts and shifts and idles just dandy, just loses power after half throttle, cuts out daaadaaadaaaaaadadadadaaaadadaaaaaaaadadadadaaaa<< <thats what it sounds like, not slow up and downs but instant and never gains the power it should have at WOT.

[AlTn]

k..well...when you get ready to reassemble the carb...pay particular attention to the float level...only ones I've worked on..the float should be parallel to the carb body with the carb inverted...at the beginning of this forum...read the Top Secret Files...

[kbait]

I worked on a 25 once (similar carb, just a bit larger) that acted like yours does after about half throttle. I cleaned the carb thoroughly and installed a kit, and set the float 'level w/carb body inverted'. Upon testing, it still behaved the same at 1/2 throttle and above.

I then bent the float arm so the float dipped just a bit toward the carb body when inverted (effectively raising the fuel level in the bowl slightly), and it worked fine at all throttle positions. Never figured out what the issue was, but you might give it a shot if all else fails. Good luck!

[78 mckee]

It could also be a probem with the stator or the wires that feed from the stator to the power pack and coil. The wires run from under the flywheel and move back and forth with the timing advance plate. Sometimes the insulation can crack or become damaged and then the exposed wire can short out on the plate as the throttle is advanced. Your excellent description of the sound (LOL) leads me to beleive that the ignition is breaking down or is shorting when you get to that certain rpm or certain position of the advance plate. If your carb rebuild doesn't do the trick, I'd look under the flywheel for a problem.

[jmendoza]

on those models the top of the carb is plastic and warps, causing an air leak, Machinest has a good picture on his site of how he adds an extra screw to it to hold it flat so it seals...later models incorperated this. Check o ring in fuel line connectors, and look for air leaks where fuel lines go on the barb fittings.

[Akfish42]

Thanks kbait,

That gives me a bit more hope than just another cleaning of the carb. Especially since gas down the throat had no affect. I'll put it back together tomorrow after a thorough soaking and give it a try. If that doesn't work I'll try adjusting the float for higher gas level. I don't want to do it during this assemble because I won't know if it was the float or just something in the carb.

I wish pulling out the fuel system on this was an olympic event. I think I could do it in my sleep at this point!

Thats a nice walligator, I sure miss catching and eating them. I used to live near Finland, MN.

[Akfish42]

Thanks jmendoza,

Yeah I've looked extensively at the machinist pages, a great resource. Mine has the extra screw on top of the carburetor(7 in total) and everything is sealed air tight. I'll be putting a new kit into it tomorrow. I have put hose clamps on all connections and there are no leaks.

Nice looking set up you have. Mines a 1955, 14.5' Elgin with this sick 9.9 on it.

[Akfish42]

Thanks 78 mckee!

Yeah, well I'm glad someone actually gleened some input from my sound description! I have thought from the beginning it was spark related because of the sound/way it was reacting. Always at exact same throttle setting no matter how quick you throttle up. No effect pumping bulb, no effect squirting gas into the carb.

Hopefully I'm wrong, and I'll be zooming around tommorrow morning at WOT! Otherwise I have to order and wait for more parts!

[Akfish42]

Well Bad News! I'm 99.99% sure the problem isn't fuel related now. I tested the motor this morning after a complete carb rebuild and it does the exact same thing! So now I guess I need to look at ordering Power Pack, Coil, Charge Coil, Sensor, Stator Coil. Is there anything I'm missing? I know I wont need all these parts, but iboats says they will take back what I don't need. My family will be here in a week, so I'm going to have to overnight or second day air these parts. PLEASE HELP!

Thanks