52 Johnson TN-28 - running, but not well

[ShoestringMariner]

I got my TN-28 back together. It's my first outboard ever, classic or not. I went through the carb, doped the float and reassembled. No drips from the primer or the carb anywhere. The coils were baked, so I replaced those and cleaned the points. Getting it running was not as easy as I expected, nor did it run more than a few seconds before flooding out. I tried tweaking the low speed, high speed, priming,,,nothing could get it running more than a cough or a brief few seconds.

I suspected the fuel as it was 6 month old (premium with stabilizer) and I think I mixed too rich (small batch in paint cup), so I dumped it and started out with new premium and a more careful mix, perhaps even on the leaner side. I put new plugs in it and finally got it running. At first it would only start out of the tank and barely run. It would die as soon as I tipped it in the water. Then after setting the low speed to 5/8 or 3/4 open, it ran and stayed running. There was a lot of backfiring through this y shaped fuel manifold type thing attached to the crankcase, like a shot of compressed air. It seemed to do this more when in neutral as opposed to in gear.

No matter what I did, I could not get this motor to really rev. I don't know if it is running on one cyl or not. It would idle somewhat low with a few misses here and there, and run full throttle but not revving at all like this vid (this is a vid of a TN26). Nothing I did with the high speed idle made any difference unless I closed it completely.

Any thoughts?

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[racerone]

The " Y shaped fuel type thing " is the low speed mixture adjustment at the rotary valve.-------When air spits out of that hole you need to open the low speed needle some.---If you have been running it dry then you will now need to replace the impeller.

 

[steelespike]

Premium gas is actually harder for your motor to burn.That's not your problem but a huge waste of money.
I hope your mixing 1/2 pt. to a gallon.?
Disconnect one plug wire at a time see if it will run.
Usually on one cylinder it would still seem smooth but lack power.
Usually struggling in the water indicate a lean condition.Though there are other more serious conditions
that would make it struggle.

 

[tomhath]

Is it getting a good flow of fuel from the tank to the carb? The petcock should have a strainer, either that or the shutoff valve itself can easily get partially plugged which will cause it to run lean.

 

[ShoestringMariner]

Thanks guys.

Steeles; I run premium because of the ethanol content in regular fuels in my area. I did not know it would be harder to burn...figured higher octane was better(?) I mixed it 16:1 in a mixing cup. What is strange to me is that the high speed adjustment made no difference at all. I followed this article to a tee. http://www.pochefamily.org/outboard/CarbService.html

Racer; I have a new impeller for it, so I didn't worry much about the old one for the initial firing, but yes, I do agree with you...not a good idea. I fiddled with the low speed, and found it worked best at the advertised 5/8 open, but the sneezing still happened occasionally.

 

[F_R]

No need to mess with it any more until you find out if it is running on both cylinders or not.

 

[ShoestringMariner]

Thanks, I was just messing with it. Got the sneezing to stop, and running pretty well, to the point of starting first pull every time. Did not want to stay running at first, had to keep pumping the primer repeatedly until it ran on its own.

Then after about 20 minutes, this grey spooge started oozing out at the pivot stem(?) http://i1372.photobucket.com/albums/...pslclttuww.jpg
http://i1372.photobucket.com/albums/ag337/ShoestringMariner/photo 3_zps6vassm5r.jpg

Lower shaft seal issue?

 

[silver_bay]

My understanding is that higher grades of gas are blended so that they don't "detonate" (aka knock) without spark in higher compression engines.