Johnson 15 hp motor die's on full throttle

[arctic_dan]

Off with the carb again. Will check the bowl vent again. I know it is not plugged. But maybe its semi plugged and not letting enough air in.

 

[oldboat1]

Are you completely disassembling and soaking, arctic_dan? Need to take off core plug(s) but leave lead shots in place. Leave the linkage in place, but soak top and bottom after disassembly, then blow out every hole with carb spray. Check condition of the needle, and make sure the orifice isn't blocked (good to test needle fit with the plug out so you can see it in place.)

 

[arctic_dan]

Thats what my plans are for tomorrow. I will soak the carb and blow it out. Ive got the carb apart again and inspected it really closely. In my wives kitchen. Serious stuff. Everything checked out nice. No blocked holes. I will soak it tomorrow and see what happens then. I may also try the gravity fed fuel as mentioned. At least like that we will know where the problem is.

Can anyone tell me what the 3rd part from the bottom the left is? The little white part. Where does it go?
https://www.amazon.ca/Evinrude-John...qid=1496543835&sr=8-1&keywords=johnson+398453

 

[oldboat1]

There is sometimes a bushing that fits in the needle valve passage, but don't think you have one in your model. Other than that, not sure what the part is.

Got a timing gun yet? Will tell you if you have spark loss at high rpms, or rule out that issue.

 

[arctic_dan]

I will be receiving it this week from amazon. Ok. I was just wondering about that little part because the previous owner had gave me spare parts and that part was in it. Wasn't sure where it went. After Im done soaking and cleaning it and checking with the timing light I will either drill out the main jet a little or get a bigger one if possible, If they even sell larger ones?

 

[jbuote]

Granted I'm a complete newbie to outboards, but not to engines in general...
​Unless you have precision machine work equipment, I would NOT drill out the jet to make it bigger...
​They are precision orifices, and you don't even want to scratch them with brushes, wires etc... Throws them out of spec...
​
​(EDIT: Also, without precision machining tools, you'll never get the accuracy you need to get, to have it worth anything at all...
​Would probably make things worse actually...)

Just my 2 cents....

 

[AlTn]

may be time to look for air leaks instead of increasing the fuel supply at higher rpms....have you checked the crankcase to block seam?...carb to intake gasket?..fuel connector, hose to pump, and pump to carb hose clamps?...upper and lower crank seals?..by pass cover gasket?

 

[arctic_dan]

Im in the process of soaking the carb and I have my timing light now so when I get a chance I will rule out those things. jbuote For the price of a main jet I think its not a big loss to drill her out and see if it would solve the problem actually. Ive done so many time on my snowmobile engine just to rule out certain problems Thats why I was wondering if I could get bigger jets for this? Very sad if you can't. AlTn Ive checked over and over these darn gaskets. Is there a video or tutorial on how to check crankcase seals etc. Those are things I havent been able to pull the flywheel off yet so I dont know if a crank seal could be leaking.

 

[AlTn]

on the upper you can put some oil around the seal and look for bubbles as you pull the motor through < plugs out makes this much easier,but you probably knew this already >...even though I mentioned the seals, in my experience with 2 strokes, crank seals have more of an effect on idle issues. I dunno, maybe revisit the fuel flow to the carb at wot if the spark remains strong on your timing light test.

 

[8928hpj]

If it is running better when you pull the choke then you have a fuel starvation issue.. I would re check your Fuel pump diaphragms. Or you may have a blockage somewhere in the lines.. Does it have a fuel filter somewhere?? Id change that all so even if it looks new..

 

[arctic_dan]

Thank you for the suggestions guys. Will get back to you. 8928hpj . Ive went through the gas tank, All the connectors, Fuel pump to carb and not able to find a single thing wrong. That's why we are trying other things. I was thinking maybe to bring it to a shop but I know the scenario. I pay $$$ and it stays with the same problem. To many shops are like this now days. Especially since they cant test it unless they put the motor under load.

 

[arctic_dan]

If it happens to be the crank seal can anyone confirm if I have to split the motor or not?

 

[AlTn]

do not have to split...the factory has a special puller, but I used a technique I saw on youtube...carefully drill a couple of small holes in the seal trying to center them in the seal...screw a couple of thin wood screws into these holes, then work side to side lifting the screws up and the seal out...the "trick" is to not knick the upper crank while drilling..the vid showed using the closed end of a combination wrench around the bit to keep it off the crank surface...anyway this method worked flawlessly in practice if it comes to this

 

[racerone]

To inspect the bottom seal you need to remove the powerhead.---Then remove 3 screws to pull seal holder out.

 

[ondarvr]

Granted I'm a complete newbie to outboards, but not to engines in general...
​Unless you have precision machine work equipment, I would NOT drill out the jet to make it bigger...
​They are precision orifices, and you don't even want to scratch them with brushes, wires etc... Throws them out of spec...
​
​(EDIT: Also, without precision machining tools, you'll never get the accuracy you need to get, to have it worth anything at all...
​Would probably make things worse actually...)

Just my 2 cents....

​Drilling out jets isn't that hard, you just need small enough bits, you aren't trying to match any existing spec, just going larger in small increments.

 

[arctic_dan]

I think we have a lead. Still in the yard I tried Leaning out my low end screw. So it would run rough, Just to say it would idle. I then Sprayed Brake cleaner around the crank seal under the flywheel and the motor started to idle better. I will do the timing light test you suggested as well as I have my carb all cleaned out. Welch plugs removed. Soaked In parts cleaner and blew out with compressor. Put new welch plugs and after this test I will go ahead and pull the flywheel off to see whats going on there. I will post my findings.
AlTn from what I've experience on snowmobiles, If a seal is leaking it will effect bottom end yes but it will also translate to a lean condition on top end. Usually leading to a blown motor. I just hope I haven't started doing damage to the top of the piston.

 

[arctic_dan]

Did a quick check today on the crank seal and didn't find anything which I find odd. Put oil around the seal, spinning the crankshaft and found no leaks.
https://www.dropbox.com/s/hvnc5eca9ze3rcb/DSCN3103.JPG?dl=0
https://www.dropbox.com/s/po2cbmvw9i1glrn/DSCN3102.JPG?dl=0

Next check will be when I go on the water to see if the carb cleaning did anything and the timing light check.Which I need a battery now to power the timing light.

 

[8928hpj]

Keep us posted I'm curios to what the issue is now..

 

[arctic_dan]

PROBLEM SOLVED!!

I changed the crank seal and my problem was fixed. Even tho It showed me no signs of leaking at WOT it was a different story. Even if the trick of oil on the crank seal shows no leaks doesn't mean it does not leak. There may have been a minimal leak and everything at WOT is amplified. Since it was only a $10 seal it was a small thing anyone can do without breaking budget and best part is you don't even have to split the case. Here are some pics of the seal I changed and the victory video on water. Id like to thank everyone that pitched in on this post and hopefully It can help others out.
The timing light I purchased is a Innova 5568 pro off of amazon. It showed the motor go up to 6100 and stayed there. The flickering light was perfect and stayed lit at WOT with no misses. The camera does not pick up the flickering light very good.
Thank you again. Finally after 2 years I can lay this problem to rest with arms high!

https://www.dropbox.com/s/gtmiif1lu3o1cir/DSCN3105.JPG?dl=0 Pull out old seal with 2 screws and cap the end with the shaft with its nut to give yourself a prying surface.
https://www.dropbox.com/s/mj12hdr46wq4ou8/DSCN3106.JPG?dl=0 Reinstall new seal, filled seal with grease and lubed everything up. Used the perfect size socket and tapped it with a hammer until it seat against the lip. " Lip behind the seal "
https://www.dropbox.com/s/km0kfg34j55n5bq/DSCN3107.JPG?dl=0 Crank seal replaced

https://www.dropbox.com/s/834fgqtszjzxap9/VID_2017-06-16_13-12-03.3gp?dl=0 Victory lap around the lake.

 

[Starboardlean]

Sweet Victory