'98 Johnson 50 hp idling issues

Hello all, I am having some problems with a '98 50 hp Johnson. I'll describe the symptoms and let me know what you think. I've tried everything I can think of. We first got the boat about a year and a half ago. The previous owners said they had the carbs rebuilt and it does look like it. For the past year it has ran great. This summer it has declined more and more every time it's been out on the water. It would crank and run, but rough, WOT was great. Once it got started it would run long enough to get in gear and once it did it would run fine but then would die upon returning to idle. The other morning before hitting the water, I cranked it on the muffs and seemed to be doing fine, ran it for about 3 minutes and thought "it's good to go." Got to the ramp and in the water, hard to start. Again though, once it did start and get in gear, it was fine. Got to the fishing spot, fished a while, went to crank it up and finally got it cranked long enough to get in gear and back to the ramp. My question is, what are some possibilities that would make it run great at speed but not idle? I can't even get it to start up for more than 3 seconds now.

Things I have tried:
adjusting linkages (seemed to help but not long)
checked all fuel lines and everything seemed great, bulb holds pressure nice and firm, fuel pump is working as normal
The red schrader valve on the electric choke primer does have two cracks in it that fuel would leak out of when choking, I can blow air through the cracks so I'm thinking maybe it could have been sucking air in from there? have a new one on the way.
spark plugs are getting spark
it is getting fuel (spark plugs have fuel on them)
gas is fresh, oil mix is right
All electrical is in good shape, no broken/melted/cracked wires, all connections are good, etc.

Any help is appreciated.

Don't want to take it to a shop because I don't want to wait weeks to get my boat back and summer be over; but looks like i may have to

Sounds like you've got something gumming up your low speed fuel circuit on the carburetor. Not sure if you are willing to do a little work on them yourself, but you'll likely have to pull all three of them off and clean each one. It's not unusual with the alcohol fuel blends.

If you're willing to dig into them a bit, it's not really that hard. Just make sure you take note of the position of your slow speed needle on the top of the carb, just above the throttle linkage. Before you remove it, screw it all the way in gently and count how many turns it takes to gently stop the needle from turning. This is where you'll want to set it when you replace the part later.

The best way to clean the carbs is to remove all of the components you can and then place all of the metal components in a can of carburetor cleaner and let them soak for a night. After removing them from the dip can, blow everything off with a can of ether or carburetor cleaner. Re-assemble and adjust the linkages to be consistent across all three carbs.

I just finished doing the same thing with my '77 3 cyl 70hp last night. This thing had been sitting in a barn for about 8 or 9 years and the jets were completely blocked. When I put it all back together, it fired right up.

Good luck!

Thanks. That sounds about right. I was hoping to avoid rebuilding and cleaning the carbs but it's no problem. Guess I'll try that next and see if it'll work. I try to avoid fuel with ethanol, but it's getting harder to find ethanol free gas. That's probably why it has progressively been getting worse and worse. Over time, the ethanol probably just keeps building and building gunk in there.

I agree. Sounds like you have some build up or blockage of the idle jet. You could spray something in the carbs while running to see if it reacts at idle. If it does, that one is probably good. If it doesn't, that's the one that needs work.

[url=https://www.tinboats.net/forum/viewtopic.php?p=362684#p362684 said:

huntinfool » 3 minutes ago[/url]"]You could spray something in the carbs while running to see if it reacts at idle. If it does, that one is probably good. If it doesn't, that's the one that needs work.

Click to expand...

Let me expand on that...

Don't spray carburetor cleaner, or starting fluid or any other cleaning chemical in the carb while it's running. These cleaners work really well and will strip the oil from the cylinder walls when it is running. Best thing to do is use a 50:1 mix in a spray bottle and see if the carbs speed up. That would be the one to work on.

Good luck!

Cleaning the carbs ad everything looks pretty clean and all passages open. In the pic is that needle part supposed to be somewhat bent like that? It's like that on both carbs.

The one in the center is fine. Had a few apart and they have all been like that.