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76 jhonson 15hp no spark

I didn't want to start a new thread so just figured id keep this going. The 1974 I bought runs great now that I cleaned the carb and rebuilt the fuel pump. but I notoced when I choke it gas runs out of the butterfly. Is this normal when its running is it just flooding itself out.
 
joereeves said:
If, when you choke it the engine doesn't start... that fuel has to spill over somewhere.
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I figured as much just wanted to be sure. I found a post of yours on setting the carb follwed it to a T and it starts and runs perfectly. im glad I found this website it has helped tremendously.
 
If a plastic float chamber, it could be warped. If so, dress it up with #400 wet/dry black sandpaper... the sandpaper wet down with mineral spirits.

Could be a float set wrong. If so, correct as follows.
********************
(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

********************
 
Now don't forget the compression report on the other 15 to see if it goes up or down as you lake test it.
 
I finally got to lake test the 15 that went swimming. it definitely seemed underpowered. but it was a heavy old fiberglass boat and about 400lbs of ppl on the boat. That may have been the reason but it starts so easy and runs awsome. im going to compression test this week since ive got to run it a little.
 
When you are concerned about under power it is a good idea to do a cylinder drop test to confirm both cylinders are firing. With insulated pliers, pull one spark plug boot at a time. If the motor stalls, then you know the other cylinder was not firing or is very weak. Those motors can run remarkably well on only one cylinder but with significantly reduced power at the top end. At idle you would never know only one cylinder was working, without the drop test.

I suspect your low compression cylinder was never firing and hence why you noticed the reduced power. It was a heavy load you were pushing but those 15Hp put out a lot of punch, when opened up, so a cylinder drop test might shed some light on the issue.
 
I will try the test but both cylinders were firing fine. I took the motor out again yesterday and with 2 guys in a light aluminum boat it did fine.
 
I did another compression test today after running the motor twice on the lake. now both cylinders are between 90 and 95 psi. im happy with it for now
 
That is not bad compression for what its been through. After a few more gallons of fuel, check compression again. If it is exactly the same, then it may live out a decent life.
 
ive been renting a tester from oriellys thinking about just buying one. is there a brand you would recommend. I was happy to see both cylinders were the same readings.
 
I just had a no spark issue on my 9.9 and it turned out to be a broken core inside of a spark plug even though it made spark to the block it didn't make Spark across the electrode Gap
 
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