'76 Johnson 85hp choking out at high RPMs?

[basbalj288]

Hey guys and gals. I have a problem that nobody seems to be able to answer for me. My 1976 85hp Johnson seahorse is a great motor that has not given me too many problems at all. Unfortunately now on my first trip to the lake after taking it to get tuned up at a marina (probably my first problem) my motor had some periodic temper tantrums that I've never experienced before. The first time I full throttled the motor, the engine never "kicked into that upper gear" meaning it never got over 10mph and it didn't sound like it was getting full power at all. BUT then it gets interesting. The next time I turned it on, it throttled up perfectly and never missed a beat going 40 mph and getting plenty of power(just like it used to). This went back and forth for 2 days sometimes worked flawlessly and sometimes couldn't kick into that high gear even when full throttled and just sounded as if it was choked for air or gas. And other times it would be running poorly as if it were choked out and then all a sudden it would kick into gear and the motor revved up to normal power and we took off. :facepalm:
I took the engine cover off at one time to watch the throttle arms and the choke lever while throttling up and everything looked fine and it ran fine and then it would look like it was all working fine and it would run poorly and like it was choked and then it would kick into gear....AHHH!!!
Does anybody have any ideas because I am completely stumped!?!?

Could it be a bad gas line from my external gas tank to the motor or would that be too easy a fix?

 

[SigSaurP229]

Re: '76 Johnson 85hp choking out at high RPMs?

It could be that or a restriction in the high speed jet on the carb. Is the gas tank venting properly?

 

[boobie]

Re: '76 Johnson 85hp choking out at high RPMs?

If you just had it into a marina I'd take it back to them and see what they screwed up. Was it running okay before you took it in, or was that the reason you took it in?

 

[basbalj288]

Re: '76 Johnson 85hp choking out at high RPMs?

Yes I made sure it was vented and even ran it without the cap on at all. I took it in because the throttle cables weren't properly tuned and it was starting in gear when the control was in the neutral position so I just thought they would quickly tune it up and replace the neutral safety switch. I thought it wouldn't hurt anything because I've had the motor for 2 years now and I've done all the work on it myself and I'm a 23 year old kid who learned pretty much everything from this website and a manual so I thought it might be a good idea to let a Pro look at it for once and make sure everything is good and properly tuned.
Could this possibly be from being winterized improperly maybe?? I'm thinking about running some carbon cleaner in the gas to help clean the system out. I've heard horror stories from people taking their boats to a marina and I took it back to them but they seem to not know at all what the problem is :facepalm:so I'm turning back to the Experts and people I trust to tell me about my boat...YALL! Haven't ever been let down by this community when it comes to fixing my motor so THANKS! Any other ideas??

 

[basbalj288]

Re: '76 Johnson 85hp choking out at high RPMs?

it's almost like the engine will have no power when I throttle it up and then it will just Have all the power like normal. And sometimes it has power and is running great and then it will just hit a bump it seems and then it's going 10mph and the engine sounds like it's running at half steam and definitely not full power. I need some HELP from yall. What could be going on??

 

[basbalj288]

Re: '76 Johnson 85hp choking out at high RPMs?

and maybe I shouldn't say "at high RPM's" because that's the problem...when I throttle it up all the way it sometimes won't respond with firing at higher RPMs while other times it will. and then sometimes it will be top speed and the RPMs will just drop off and I will back down to trolling speed. Or I will have it full throttled and it will just be trolling and then all of a sudden it will just jump to full RPMs and top speed like its supposed to have been doing. What could this be??

 

[emdsapmgr]

Re: '76 Johnson 85hp choking out at high RPMs?

Any chance that during your tuneup work that the mechanic moved the two bottom spark plug wires? If they get too close to the two bottom cowling latches, they can jump to ground. Check your clearances.

 

[basbalj288]

Re: '76 Johnson 85hp choking out at high RPMs?

He told me that he did not mess with the spark plug wires other than just changing the plugs.

Could this be a possible "high speed jet" clog/problem in my carbs?

Also, the mechanic just told me there is a short in the electric choke and that he's looking for the short. Could this have been why the motor would bog down at times and then go back to normal and then bog down ...

 

[basbalj288]

Re: '76 Johnson 85hp choking out at high RPMs?

Somebody just told me that it might be my powerpack going bad....does that make any sense??