1976 Johnson 15hp starting problem

[hugh37]

Even after installing new NJK plugs and mixing a full can of Seafoam in 3/4 gallon of fuel mix, my '76 Johnson 15hp outboard (15R76) is extremely hard
to re-start after running pretty well with the initial start. Using a large
plastic barrel filled with water, I'm full-choking to begin with, then pushing
the choke fully in for the second pull, keeping fuel pumped to the carb and
insuring the tank is vented. It's only after waiting a long while am I success-
ful in re-starting. After running 3-4 minutes and shutting it off, I'm not
successful in re-starting, although it appears trying to. I'm using the correct
NJK plug, gapped at .035, and have tried gapping at .030, with the same
results. A friend has suggested a condenser problem...does that sound like
the problem? Also, I've tried different rich/lean settings. I'd greatly appreciate the expertise out there in helping me resolve this headache of a problem. Thanks much, in advance!

[hugh37]

1976 Johnson 15hp starting problem

The plugs, of course, are NGK, not NJK, and are #B7HS. I realize that Johnson recommends the Champion plugs, but I'm satisfied that's not my
problem. Again, thanks...and please respond, if you will. Hugh

[Seahorse]

Greetings from Sweden !

New to this forum but experience about the same problem with my 1976 35hp;

Bought it this summer and have done perfect 10 hrs until yesterday, when after a 30 minute full throttle journey it failed to start afterwards (2-3 minutes after shut off).

So we left it overnight but problem remains, does not start... not until I finally in desperation gave it full throttle, choke and cranked the engine for 10-15 seconds.

Then it brought us home the same half hour trip, but problem persist, it will not fire up without the same treatment, full throttle, choke and cranking 10-15seconds.

One thing though to add, when we were about to arrive the jetty at home, I accidentally managed to stall the engine, but it fired up fine immediately after that (seconds after), but after being tied to the jetty for a few minutes problem is the same, it wont start unless given the aforementioned treatment !?

Grateful for any advice so I know what parts to target !

Cheers

[Seahorse]

Should add, that while being stranded on the lake, I checked spark on plugs but found it a bit vague, but then again, it was in full sunshine, how much spark should one see really ?

I also checked fuel filter which was clean and had petrol coming plenty.

Not checked is compression, the air filter for blockage or whether that fuel really reaches the carb...

Should one suspect the coils..

Or does the -76 has the so called "powerpack" which I see many say is the culprit for similar behaviors...?

Thanks !