2000 - Johnson 50 HP Idle Issues

[jrdbrn]

My dad has my grandpaws boat. It is an aluminum haul with a 2000 Johnson 50HP (J50PLSSM). It has given us problems always and I decided to try and work on it since my dad doesn't have time. Believe it or not, the boat has sat for at least 6 years and it started on the first crank once I primed it. I was kinda amazed, but the issue we always had is still occurring. It will run fine for 5 minutes... then turn off. No excessive smell of gas besides your normal gas/oil mix burning.

Back before it sat, we had it worked on by 3 different mechanics. None got it working long. I believe the last guy had it working good at his shop. We took it fishing and didn't make it an hour before it started acting up. That's the last time I remember using it.

So, I kinda looked around. Made sure the hoses were fine and they were. Spark plugs look clean. So I primed it again and turned it on. Took a few tries, but it ran. When it started to die off, I pressed the throttle and it ran fine for 30-45 seconds then wanted to die again. I kept pressing the throttle and the issue would be temporarily resolved. Obviously this isn't a viable solution.

Anyone have an idea? Wouldn't those mechanics have said it was the fuel pump when we brought it in if that was it? It's a pretty expensive part LOL. They could have made a pretty penny on it.

 

[ondarvr]

Re: 2000 - Johnson 50 HP Idle Issues

I assume when you said pressing the throttle you meant pushing the primer button or key in. If this is not the case please say so.

When it starts to die try pumping the squeeze bulb in the fuel line, if the problem is the fuel pump this will supply fuel and it shouldn't die.

If this doesn't help then the fuel pump is most likely good, this leaves a possible air leak or sticking float needle.

If you meant you did move the throttle forward and it worked, then it sounds like a dirty low speed circuit in the carb.