2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

[SweetD]

All,

I had a strange set of occurences happen with my 2005 Johnson carbed 2 stroke 90hp today and I am asking for some diagnostic help please...!

The problems first started this morning as I started the motor. I noticed a sheen of fuel / oil bubbling up from underwater, what I would assume is coming from the exhaust. I premix my oil and fuel.

I ran the boat fully loaded with people to the beach and it seemed to run fine. When I got to the beach I took off the cowling and visually inspected as much as I could / pumped the bulb, etc. Did not see any fuel leaks on the intake side.

Started the motor up again and seemed like the oil in the water had subsided. Was running smooth at idle.

I will note here that I did suck up some sand last week and I have had to remove the tell-tale restrictor a couple of times and let the motor flush, replacing the tell-tale restrictor cap and it is peeing really strongly. I replaced the water pump prior to the start of this season so it is new as well.

So on the way home I open the motor up and after about a minute on plane and at about 4k RPMs the "HOT' alarm starts sounding and the "HOT" idiot light on the smart tach comes on. I dialed it down and we were pretty much at the dock.

So, anyone have any ideas on what I might look for? At the dock, the motor sounded like it was running rough, maybe even missing a cylinder. Is it possible I have some restriction in the cooling system that is not showing through the tell-tale? T-stats clogged up or something? I'm also wondering if my two problems are independent of one another or related?

Any help or advice is greatly appreciated - I have family coming in tomorrow and the boat is a big part of the plan for the visit!

Thanks,

Dave

 

[jakedaawg]

Re: 2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

as for the fuel in the water I would guess that you were probably flooded.

As far as the overheat goes, Instead of flushing the mortor by removing the restricter that you talk of I would suggest reverse flushing. I do this by removing the lower unit. I then make a hose that has no fitting on the end. I then press this over the hole in the top of the cyllinder that the tell tale hose usually attaches to. Run the water for awhile, it will come out the water supply tube. Catch it in a clean trash can if you like to see if you got anything to come out.

Thats where I would probably start after verifying with an infared thermometer that I was actually overheating and didn't just have a bad sensor. Also make sure that you premixed at 50-1 as a leaner fuel oil ratio will lead to excessive heat.

 

[SweetD]

Re: 2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

Jake - thanks very much for the advice!

Dave

 

[Noltz]

Re: 2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

I'll mention that sand will quickly destroy the seals in a water pump. Your impeller & housing may need to be replaced again. If I get rusty water through my air tools (they're similar vane-type motors inside) you'll destroy the tool if you don't clean it out immediately. Got two air ratchets that are now good-for-parts that can attest to that.

 

[SweetD]

Re: 2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

Thank you Noltz for the advice...man I hope I don't need to do the water pump impeller and seals again...but I will certainly consider it!

Dave

 

[SweetD]

Re: 2005 90hp Johnson carbed 2 stroke - need some diagnostic help please

I would like to report back that I pulled the t-stats and flushed them out, and ran the motor with the t-stat covers on but the t-stats removed, in order to flush the sand through. The motor ran great all day with a day full of pulling the tube with the kids, etc. So I think it's good for now.

Dave