15HP Johnson Idles but dies at throttle

[AriseKillEat]

I have a 78 15hp Johnson that has never given me any problems until today. This motor has always been very easy to crank, but to day it took a while. When it finally started I put it in gear and it died. Started again idled fine, put it in gear and it dies. So I started it again it idled just like always so i give it a little gas in neutral and it died. After playing with it a while got it to run with the choke pulled some and went on up the river, pushed the choke back in after running a while and it died automatically. This was the first time its been cranked since duck season and it was running great then, and I always unhook the gas and burn the gas out before pulling out of the water. Any help or suggestions would be greatly appreciated.

 

[marinemech1]

Re: 15HP Johnson Idles but dies at throttle

[ and I always unhook the gas and burn the gas out before pulling out of the water. Any help or suggestions would be greatly appreciated.[/QUOTE]

Time to clean carb p.s. where in the manual(s) does it say to drain carbs.???
Wayne

 

[Rick.]

Re: 15HP Johnson Idles but dies at throttle

I'll vote for a good carb. cleaning as well but it could be a bad fuel pump although I don't quite know why it would die so suddenly. I would normally expect it to stutter a bit before it dies. Does the prop turn freely when motor is in neutral? If not it could be a gear case problem but lets hope not. Best of luck. Rick.

 

[Jungleboat]

Re: 15HP Johnson Idles but dies at throttle

Ahh... I came here because I'm having exactly the same problem with my 90HP V4 (1980 ish)

It's actually an improvement, as previously it just wouldn't start when somewhere between hot and cold. Now with the correct plugs and plenty of fuel-bulb squeezing it's actually quite easy to get it to fire and run on idle.

Open the throttle though, and it dies.

I don't have the problem of needing choke once running though?

What I did, in order to get home, was put it into gear and then just leave it. Once the boat was moving forward a bit and had some momentum behind it I was then able to give it a tiny touch of throttle, then waited until the revs were spinning freely. Another tiny touch and again waited until it had caught up. Then a third tiny touch more, waited until it was around 2000RPM (guessing, no tach'), and from there I could open it up and it ran as normal.

One thing that occurred to me was maybe outboards cool down a lot faster than car engines, being in the water an all?

To operate the choke on my engine you have to push the key in while cranking. I don't even know if that works while the engine is running? Can you just hold the key in without cranking? I'll have to try...

But yeah, I'm also looking for guidance on an engine that dies when you open the throttle.

If a car or bike I'd say it was obvious it was cold and needed choke - but it has been running for 30 mins and then stopped for 20. Does such a big outboard get cold enough to need choke again after 20 minutes?



JB

 

[bigbugin]

Re: 15HP Johnson Idles but dies at throttle

I'm having the exact same problem as JB with my 2002 90hp...and have getting run around in possible solutions ...I use my boat in the ocean and it sucks that sea tow has to bring me back in every time..and putting on the trailer is the biggest mission in the world cuz it dies everytime I give it some juice ..