15 HP Yamaha 2 stroke--won't pull

Jeff Reardon

Jeff Reardon

Well-known member
Older model, early to mid 90's. I've had it for 10+ years and am at least the third owner.

It was last used last December.

Went to take the boat out yesterday and found that the starter cord will not pull at all. Engine is in neutral, but the starter cord appears to be locked as though it were in gear.

I'm a mechanical nin-com-poop. Any suggestion on how to diagnose what may be wrong?
 
Jeff,

Pull the cover off and see if you can turn the flywheel by hand. Try a wrench on the nut, and turn in the direction that the rope would pull it. If it turns there, there is just an issue with the pull start setup\.

If you cannot turn it, it would seem that the motor is seized up. When yo last ran it did it ran and stop normally? Pull the plugs and shoot some oil in the cylinders to see if that loosens it up.

God luck,

Art
 
On a stand or on the boat.....take out the spark plug/s, put it in gear and turn the engine over with the prop or flywheel. If it turns over then it's the starter rope/rewind assembly...if it will not turn over then it's more than likely the engine. In the latter case turn it face down on the floor and put some oil (don't fill it full just a couple of teaspoons), probably some type of penetrating oil or even just diesel oil, into each spark plug hole. Let it set a day or two and then try to free up the engine by using the prop again as your tool.

I have used this method on old OMC engines and after they were loose just run them and they polished up just fine from where the rings had rusted /seized to the cylinder walls. My father showed this to me and it worked just fine. Probably a much better solution if you were a real outboad mechanic but this is a "farmer" fix.
 
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First rule; DON"T force anything. Forcing it to turn over may damage the motor, especially if the piston(s) are stuck. Pull the plugs, squirt some oil into the cylinders, let it soak over night, THEN try it again. It should turn over freely at this point (with the plugs still out). If it doesn't, then based on your admitted knowledge, it's time to take it in to a shop.


PS. Brad types faster than me. :>)
 
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I just had the same issue with a Mercury 25. Ended up being a busted rod in the engine. 2nd time using the motor, never heard a single noise before it was shut off for the last time.
 
That's why you don't force it....it could be much more than just a stuck/rusted ring....so don't compound the roblem by breaking something else. "Get a bigger hammer" is not the answer here. :-) If the oil soak doesn't work then it should have the head pulled to see what's going on inside the block. My father had went as far as using a block of wood and tapping on the piston top with the head removed to get it loose. This was in a 58 Evenrude 18hp. When he eventually rebuilt that motor there were numerious marks on the cylynder walls where the rings and set and rusted against the cylinder. On more modern motors I'd think this type of attempt to fix might not be wise but on these older simpler motors it's worth a try.

All this said .... I am far from an expert and certainly I am not a mechanic.
 
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Check your shift linkage. It may be in gear or between instead of Neutral. Some won't pull if they are not in Neutral
 
Yep, make sure she it in neutral. If the prop spins easily, then it is. If not, linkage problem.
 
Just a note about smaller outboards- Not sure if this is the case here but for any of you that pull the motor off your boat, make sure you do not store it anyway but vertical. Reason is water can run up the exhaust and into the cylinder. Guess what happens next time you try to start it. Hope that is not the case here but many motors have come my way all rusted up tight for that reason. Good luck with yours. Also if it is stuck don't panic, I have loosened up a bunch of them with a homemade fitting in the sparkplug hole that has a grease zerk on it. Pump the cylinder full of grease with a grease gun and it might move, messy but a good trick.
 
Many thanks to Art, Carl and others for the sound advice. I pulled the top off the motor, it turned fairly easily with a wrench, and started up on the second pull this afternoon.

It ran fine and we had a nice boat ride, but the motor stopped spitting water after running fine for 30 minutes or so. I limped back to the launch. I'm guessing this is unrelated, and will either figure out how to check the water pump myself or take it in for a repair, but am interested in any thoughts on whether it may be related to the original stuck cylinder(s).
 
The impeller was stuck to the plate in the pump, so when you started it you ripped a vane and after 30 minutes the rest of the impeller self destructed?
 
Maybe, Brad, but I'm hoping for a simpler fix.

I pulled the cowling off last night and messed around with the tell tale hole and the rubber hose that feeds it. The hose was clear, but I was unable to blow water through it out the hole. I poked around with a bit of weed whacker cord and that seems to have opened things a bit. Water will now pass out the hole.

I'll try again with the engine running this evening.
 
Maybe, Brad, but I'm hoping for a simpler fix.

I pulled the cowling off last night and messed around with the tell tale hole and the rubber hose that feeds it. The hose was clear, but I was unable to blow water through it out the hole. I poked around with a bit of weed whacker cord and that seems to have opened things a bit. Water will now pass out the hole.

I'll try again with the engine running this evening.


Jeff,

If the impeller did break apart, there may be pieces of it getting pushed through your cooling areas of your motor. If you can run it for a bit, all the while checking the the "spitter" is working, and you don't have a problem, then you should be OK. An impeller fix is real easy on your 15.

If you do want to fix it, see if Yamaha has a Heavy Duty model. It usually comes with not just the impeller, but a stainless housing and a heavier keyway, and a new rubber connector or the brass water tube. I used to be able to get them for my '77 Evinrude 6hp. I used it for trapping and Ihad to replace it every two years, as I ran in some real bad "loon shxx" to get to the muskrat sloughs.

Check online, (YouTube), as I'm sure they have a video on changing water pumps.

Good Luck,

Art
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Thanks, Art. No chunks of stuff in the hose from the engine block to the tell tale. Whatever was dislodged from the tell tale was small enough that I saw nothing but a grey smudge on the end of the probe.

I'll give it a quick run today and see how it fares. (I love being 5 minutes from a low use boat launch.)

In any case, I had fears of a completely seized engine, and now the worst case outcome seems to be a new water pump and me learning how to remove the lower unit and replace it.

I may have learned enough to progress from mechanical nin-com-poop to "knows just enough to be dangerous".
 
Dave:

If I'm going to pick a motor to learn on, this is the one. I've had it 10+ years; I'm the third owner; I got it with a boat and trailer for what the boat and trailer were worth. At this point, it doesn't owe me anything.

Lunch hour test run--ran her for 30 minutes and she peed like a frat boy at a kegger the whole time!

Thanks again to all of you.
 
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