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77 Johnson 6hp seahorse - does not start

M

mmcgarri

New member
Good evening all.

I have a 77 johnson seahorse 6hp that I have been trying to get running, but am running out of ideas. Any additional troubleshooting steps or things gs to try would be greatly appreciated.

I have been following the gas flow. First the fuel line and primer ball leaked, so now have a new one.

Then the fuel line from the motor connection to the fuel filter had cracked so this was replaced.

Then the fuel filter was leaking from the gasket. Replaced the whole fuel filter.

Checked the carb bowl, but no gas. When I took the carb apart the needle to allow gas into the bowl was not connected to the float and there always closed (not sure where the metal connector went). I used a carb kit and fixed it.

But still the engine will not start. If I use 'quick start' in the carb or spark plugs then it fires up , but dies out pretty quickly. So I know that there is spark and it can work. Just not getting the gas. But not sure what else to try next.
 
When you had the carb apart, did you clean out all the passageways? It is not uncommon for the high speed meter in the bottom of the bowl to be plugged.
Part #27 in the diagrams here.
 
I thought I had. I used carb cleaner and also blow out any holes, tunnels, etc. I especially remember the high speed valve, as it was a brass tube with 3 (or more small holes in it). But no harm in taking it back off and trying again. Ii will do that tonight.
 
The tube with the small holes is called the "emulsion tube". It runs up and down in the middle of the float. Don't try to remove this tube. If an engine has been sitting for a long time, the blockages may take more than carb cleaner and compressed air to clear.
 
So yesterday I took the carb apart again (twice). The first time I mistakenly put the float on upside down (doh!). This caused the needle value to not sit correctly and therefore too much gas was coming out. However in this case the engine continued to run (albeit a lot of smoke). So I took it apart again and flipped the float. I also confirmed the needle valve would shut off the gas before I reinstalled on the outboard. But now I am back to the engine not running without quick start. ☹
 
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The float should sit parallel to the bowl when upside down as a good starting point.
Just to rule them out as factors, what is the compression on each cylinder and
does the spark jump at least a 1/2 inch gap in open air?
A weak spark may be enough to light the easy start but fail to light the fuel mixture.
Same with a low compression.
 
How is your low speed mixture set? Take the nob off, turn the adjuster all the way in, then back out 1 1/2 turns.
If this gets it running, turn the adjuster in 1/4 turn at a time, waiting about twenty or thirty seconds between
adjustments. Once the engine start to stumble, back out 1/4 turn and it should idle smoothly. Then but the knob
back on with the pointer centered.
 
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