1995 60HP Johnson rubber (oring?) chunks in thermostat

[wfburton159]

I have been having all kinds of trouble with my 1995 Johnson 60HP 3 cylinder fouling plugs. It will drop to two cylinders fairly often but then come back to 3 cylinders. Seems completely random on when it does it. This past weekend I pulled off the thermostat cover and found small chunks of rubber on both sides of the thermostat. The rubber chunks looked like pieces of an o-ring. Any ideas on where the rubber is coming from? Water pumps almost instantly out of the side discharge. Once up and running on all three cylinders the plugs look nice and tan after a two mile full throttle run. So I am wondering if that rubber has been hanging the thermostat up? This has been going on for three years though so not sure of that. This weekend I will check the primer (electronic primer by key switch) for leak by when off. Its really rich on idle and mid throttle. Full throttle it will clean up. But I have the idle fuel screws set at 1 to 1 1/2 turns leaner than suggested initial setting.

 

[jakedaawg]

Maybe chunks of an impeller...? Or chunks of deteriorated diverters, not sure if those could get into the stat?

 

[racerone]

I do not believe that model has those " diverters " in the cooling system.----Post compression test numbers on this motor.

 

[wfburton159]

I haven't checked compression but the thing runs with lots of power when firing on all three cylinders. To get to the water pump I need to remove the lower unit?

 

[IDFISHER]

Here's a couple videos that should be very helpful for your motor.

Water Pump Service - https://www.youtube.com/watch?v=kYgwzSIn0Ug&list=FLgyLfgOlJTq94icdiOE2r-w&index=3&t=0s
Carb Service - https://www.youtube.com/watch?v=VDn9fAn7sjo

 

[Tim Frank]

Are you the original owner? i.e. has it ever run OK for you?

This has been going on for three years? (won't ask why you have not addressed this sooner.... There are some conditions that could cause damage from operating like this.)

As well as compression, check that spark jumps 7/16" gap....use a proper air-gap tester. (can't believe racerone did not suggest that.... )

 

[wfburton159]

Not original owner. Motor has ran like garbage since I have owned it but it has never left me stranded. It has a new power pack that I put on. Today I took off the carbs and they were spotless. Reeds in good shape as well. I might have at some point messed with the electronic choke. So I also checked that tonight. Fuel flows when energized for choke and no fuel flow when not in choke. If you turn the knob on the end of the solenoid fuel flows freely. That might have been it. Didn’t bring the compression tester. I don’t think it’s compression related as it has all kinds of power at times.

 

[oldboat1]

Sounds like you might be using one system to correct another. If the primer system is now working correctly, go back and readjust the mixture needles. Initial setting per book instructions, then adjust for best performance.

Check the water pump to see if that is where the rubber pieces are coming from, and might as well change out the impeller while you are at it. With the l.u. removed, it would be a good idea to flush up the water tube to clear passages of any debris.

 

[Tim Frank]

Why did you replace the power pack?

 

[wfburton159]

Power pack was replaced because it would never provide spark while cranking. The only time if would start would be when you would bring the key position back from start to run. It would spark in run. With the new power pack it starts great in the start key position. I will check compression and take apart the fuel pump next. This thing is a mystery. I named the boat Out Of Sorts because the engine never runs quite right.

 

[Tim Frank]

With that history, I would be suspecting a wiring issue.

But, also given the history, you are at the mercy of what the PO did....or did not.
You need to verify just about anywhere that a well-meaning DIYer might have gotten loose.

Have you removed and cleaned the high speed orifices? If not, do, and verify that they are the correct jet in each carb.
One recurring theme in this forum is the search for the Holy Grail....turning a x HP motor into a 2x HP. motor by s simple jet swap....or carb swap...etc.
Often, that does not work and the new owner gets left to try and figure things out.

 

[oldboat1]

^^+1. To include key switch wiring. Sounds offhand like the start position is wired as shut down.

 

[wfburton159]

Well I did not have time to look at the orifices this past weekend but I think they have to be too big. It starts fouling plugs at full throttle in under a 1/2 mile now with the warmer weather. First task this Thursday will be to take the airbox off and check those orifices. It is rich all the way through the entire way from idle to full throttle. I have my idle screws adjusted to about 1.5 turns when the recommended setting is 2.75 turns. I am getting so sick of this thing so hopefully this fixes it. All kinds of power when it runs on all three cylinders.

 

[Tim Frank]

See if you can verify that they are the OEM carbs and not a retro-fit...."someone said I could put 70 HP carbs on my 60 HP,,,,:"

Both HS orifices AND LS may be wrong.

 

[wfburton159]

I should also mention that this thing always runs much better with the motor cover off, with more available air to suck in. The opening in the motor cover is quite small. Carbs appear to be OEM. I really hope this gets straightened out soon. Of course the local marine repair shop didn't have the high speed orifices in stock.

 

[Tim Frank]

Why are you replacing HS orifices? They are not really a wearing part....just make sure they are correct.

 

[Tim Frank]

....and clean.

 

[wfburton159]

They are clean. Carbs are very clean. HS orifices are 47D. I believe they are supposed to be 45D according to a parts website. Are any charts available that show the elevation and air temperature to choose orifice size? I am used to these type of charts for snowmobiles and dirt bikes and such.

 

[wfburton159]

LS orifices are the correct 35D size

 

[Tim Frank]

OK.
The current 47D will deliver about 10% more fuel than the 45D, That is certainly rich and IN THEORY could give you most of your performance issues, but I do not know the practical result of 10% too much fuel. i.e. never seen it myself.
As far as tying jetting size to elevation, not sure where you are but as a rule of thumb, if you are below 5000 feet rejetting should be unnecessary, just go boating.

If you are anywhere between 3000 and 5000 feet, the effect of your o'size jets would be amplified.
I think it would be worth changing them....maybe even to 44D.

Any idea why they appear to have been re-jetted?
Are you able to ask the PO?