Motor Running Slow
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Posted on Monday Jun 13, 2011 at 1:10 AM  
I have a '90 2 stroke 25hp Evinrude (long shaft) that i just took out yesterday and it wont get up and go like it should. The throttle cable moves everything as it should and has plenty of room to go, but it wont go any more than about 10 mph (on a 16 ft jon), which is at about 60% throttle. I get no response by throttling it past that point.

It seems to me like a fuel metering/flowing problem (its not a cavitation or trim problem IMHO, b/c it has a hydrofoil stabilizer and i tried all different trims). Brand new fuel line and bulb as well. The motor doesnt sound or feel like its bogging down at a certain point, it just wont make high RPM's. I also adjusted the fuel mixture screw on the carb and that made no difference at any given setting. I am running it rich (40:1), but there is no smoking so i dont think that's too rich, but i'm a greenhorn on this motor stuff.

Should i attack the carburetor or the fuel pump first? Any thoughts and/or suggestions at all would be great. Thanks!!
Posted on Monday Jun 13, 2011 at 7:48 AM  
I would start with the carb after I knew what the compression was.
Posted on Monday Jun 13, 2011 at 3:06 PM  
Ok thanks. Compression reads 104 in each cylinder. Factory said anything over 100 and w/in 10 lbs of eachother was perfect. I have the carb kit so i think i'll do that today.
Posted on Monday Jun 13, 2011 at 3:53 PM  
what did the plugs look like.
Posted on Monday Jun 13, 2011 at 4:03 PM  
Also on that motor make sure the timing advance isnt sticking. Take the cowling off and advance it to wot and make sure the linkage it pushed all the way back and bottomed out. Also look in the throttle bodies and make sure the flaps are all the way open and even. If you tear the carbs down dont just blow them out. Inspect all the jets and bypasses for an obstruction could tell you why it happened.. That small of a rig sounds like the carbs might get ya.. For future the difference isnt 10lbs it is 10% just so happen yours was 100lbs. Once you get it running again if you haven't I would decarb the thing if you trust the increase of your compression gauge. If you dont wanna waste the money on a bottle of seafoam I can tell ya the redneck way to see if your cylinder is carbon-ed up
Posted on Monday Jun 13, 2011 at 4:12 PM  
Ok thanks for the tips. The plugs are brand new and have not looked at them since i ran it two days ago(their first use).Not sure what the timing advance is or what particular linkage needs to be back and bottomed out. Like i said, i'm a greenhorn. BTW what is that redneck way to tell if my cylinder is carboned up?

Also, if i give you the model number could you order me a parts or service manual? I see your an evinrude dealer
Posted on Monday Jun 13, 2011 at 5:14 PM  
I can but I am not a Evinrude dealer I typically wont order parts for stuff I am not working on but will point ya in the right direction as of the best price. If it is a 90 25hp I wont need the model number for the manual. The plugs will tell ya if one cylinder is leaner than the other as well as other things by the coloring. Bring one of the cylinders to TDC. Take all the plugs out and stick something in the plug hole and turn it by hand tell it stops pushing the something out of the hole. Take a light and inspect the piston head. You might have to roll the piston back a little past TDC to see it good. With compressed air blow a quick blast on the cylinder head and then look and see if it changed any. Not anywhere close to the best way but more than likely if you have had this for anytime you need to decarb it. If the motor has spent alot of time at low rpms then it will be carbon-ed. The carbon wont be a cause of your problem but will extend the life of you outboard if taken care of. You can either just as a can of decarb to your fuel system or fog it with a can of deep creep or something similar.
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