2001 Johnson 90hp running problem

[GaryO]

A friend of mine sent me this problem and I thought I'd post it here. I have no clue what his problems is. Hope someone has an idea on this one! Thanks!

> Gary,
>
> 2001 Johnson 2 cycle 90 horse. Very hard starting, starts and dies 10- 15 times till I can get it to 1400 or so RPM's then runs . Mid speed and full throttle runs fine. When bring it down to pull into dock, when it gets down to under 1000 rpm it dies out and will not start and stay running. While running at dock for 10 minutes all of a sudden, it put out heavy smoke for a second and then up to over 6000 rpm and the throttle had not moved.
>
> Bob

 

[Monte1961]

Re: 2001 Johnson 90hp running problem

Start it up, and after running, shut it off. Go to wot and look to see if fuel is dripping or running from carb/s? post back and let us know.

 

[GaryO]

Re: 2001 Johnson 90hp running problem

Hi Monte, thanks for the reply. We will not be able to get out to the boat until this Sunday to check this out. With what you want us to check, what are you suggesting "might" be wrong? It kind of suggests a carb/float problem?

 

[Monte1961]

Re: 2001 Johnson 90hp running problem

Yeah, sounds like a fuel?air leak to me. Post back and let us know what you find.

 

[GaryO]

Re: 2001 Johnson 90hp running problem

Got out to check it out today. Hard to start but got it running after cranking for a while. If we keep the RPM over 1200 it will run, anything lower it will die out and stop. So, we had it running and then we shut it down and took it to WOT and with the silencer off we could see fuel running out of the intake on #1 carb. (Top Starboard side) There was a little leakage from #3 also but that "might" have come from #1?. So, what are your thought on this?

 

[GaryO]

Re: 2001 Johnson 90hp running problem

Anybody, any clues?

 

[Daviet]

Re: 2001 Johnson 90hp running problem

If you have fuel coming of a carb, it's time to check the needle/seat and see if it is defective. Float could also cause the problem. How long has it been since the carbs were overhauled?

 

[GaryO]

Re: 2001 Johnson 90hp running problem

That's what my thoughts were also. I checked with the owner and he stated it didn't have even 50 hours run time on it and didn't think they needed any service yet. I told him it had to be a carb problem because everything else checked out okay. He talked to another friend who had a can of "Engine Tune" and drained his carbs, sprayed this stuff into the carbs and float chamber and let it foam up. He let it sit for about an hour and reconnected his fuel lines, pumped it up and started his engine. Seems to have corrected his problem from what he told me today. Said he needed to replace his spark plugs after this "treatment" but the engine will now idle.

Thanks to everyone for your ideas and advice!