1997 15 hp Johnson Starting / Idling

[domer7]

Hello - My 15 hp outboard will not stay running. I just rebuilt the carburetor and flushed out all of the orifices with carburetor cleaner. I put a new diaphragm in the fuel pump, cleaned and re-gapped the spark plugs but it will almost never start. I can pump the fuel line bulb until gas leaks out of the motor connection and the engine might catch once or twice but will not run steadily. I've tried adjusting the idle screw in and it seems to be a little better farther out when it will run, which is odd. Also, when it does start it will only start and run with full choke or with the choke slightly pushed in .

This is a very frustrating engine - it rarely has run smoothly in the six years I've owned it, but maybe most of that is my inexperience in servicing it.

Any direction would be most helpful.

domer7

 

[bspeth]

can you outline your rebuild procedure?

 

[racerone]

These are a wonderful and smooth running engine.--------Start with a compression test on it.

 

[Boobie]

Then do a spark test. Spark should jump a 7/16 " open air gap on a tester.

 

[johnnygjr]

doomer7 keep us posted, Thnks

 

[domer7]

doomer7 keep us posted, Thnks

OK,it's been a long, wet winter here in N.Cal,but finally got back to my outboard.

Checked the spark - had one weak spark so changed out that wire.
Compression was good - 105# and 110#
Took carburetor apart, cleaned it, blew out orifices, put back together, put on motor and tried to start it. Ran rough but would run bit.
Saw gas dripping out of the bottom of the carburetor - took it off the engine and found I had put the plug screw on the side of the bowl on the wrong side - the one with no hole. DUH
So, pulled the carburetor again, looked at my carb schematic and saw I am missing the high speed orifice the goes into the threaded hole covered by the plug screw. Not sure if there was ever one there from my first rebuild several years ago, or the rebuild last year.

My parts schematic calls out two different high speed orifices - No. 48 and No. 36. Any suggestions on which one to order?

I think I'm close to having a smooth running engine??

Thanks for the help!

domer

 

[domer7]

I think I figured out the high speed jet - it doesn't go in the same hole as the plug screw, it is in the side of the carburetor nozzle well. It is there, so I'm gonna re-install and see what happens.

Carb schematic isn't all that clear on that part!

domer

 

[racerone]

So, does the spark now jump a gap of 3/8" or better , yes or no.

 

[domer7]

racerone - the spark does jump the 7/16" gap I set up in the tester after changing out the spark plug wire on one side.

The engine is starting and running fairly smoothly now - also replaced all the gas.

I do have one question though - how much "shimmy" is the engine supposed to have? When running at idle, the engine has some side-to-side movement.

I appreciate the help here. I think a lot of my issues are learning how to clean it, always run out the gas, increase the maintenance cycle in a few areas.

Thanks,

domer