25hp Johnson-Oily slime from exhaust...

[laujok]

I have 2000 year 25hp Johnson that i bought last summer with idle problem. I tried it last year on the water and it wouldn't run at all. It stayed on idle about 10 sec and then it sneezed hard. Checked the plugs (QL77JC4), upper was white and wet, lower black and wet. Spark jumps 7/16 as it should. Head gasket, exhaust cover gasket and left side cover gasket? (where fuel pump is mounted) are new. I sanded the head and exhaust cover+baffle so that they are flat. I think that the head was warped a little. Carb is rebuild. Link n' sync is okay. Now it runs pretty fine with muffs on but oily slime comes out from exhaust and plugs are just like before. Idle mix screw is out only about a half turn. I tried 1.5 turns and 2.5 turns out but almost stalled and smoked like hell.
Running but not perfect...

Any ideas?

 

[Daviet]

Re: 25hp Johnson-Oily slime from exhaust...

Static setting on the low speed jet should be 1 1/4 turns out from lightly seated.
I wounder if the oily slime is unburnt oil/fuel mixture because the carb is not functioning properly.
Sounds like it might be time to overhaul the carb.

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

Carb is rebuilt. I will try with 20hp carb from another motor if that solves the problem.

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

By the way, if upper plug is white and wet and lower plug is black and wet, how can you tell the difference if the wetness is fuel mix or water? By smelling them I can't tell the difference.

 

[AlTn]

Re: 25hp Johnson-Oily slime from exhaust...

your upper plug may not be firing thus looks like"new". Can you see any tiny beads around the spark plug electrode when you take it out?..never noticed fuel mix beading ,but have seen tiny beads of water on the plug. Roll the piston up and peer in with a light..does it appear "steam cleaned" or just wet and black on the piston top?

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

Okay, thanks.
When I took the head off the upper piston looked black and wet but had no carbon. Lower looked black and wet with some carbon in it. Strange thing is that the motor runs pretty hard and smokes when the idle mix needle is turned out 1.5 turns. Runs pretty fine when out about 1/4 to 1/2 turns. Haven't tried on the water yet after resurfacing the head and exhaust baffle plate+cover. Head gasket and exhaust cover gasket are new.

 

[AlTn]

Re: 25hp Johnson-Oily slime from exhaust...

check that each plugwire delivers a spark that will jump a 7/16" < 12mm? > open air gap

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

spark jumps okay 7/16" on both cylinders, coils are good, power coil is ok, trigger coil is okay too. When I disconnected upper spark plug wire motor idled about 10 secs an then stalled. When I took the lower one off it stalled immediately. Both spark plug gaps are wet when motor stalls and doesn't want to start again. I took the exhaust cover off and there was wet oily lookin stuff in the cover and in the exhaust channel. I think that the cover was a little bit warped. But if this whole thing is not about water what is it? I'm running out of ideas...

 

[AlTn]

Re: 25hp Johnson-Oily slime from exhaust...

do you have a model no.?...sounds like that upper cylinder isn't pulling its share of the load

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

do you have a model no.?...sounds like that upper cylinder isn't pulling its share of the load

j25rsse

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

year 2000. tried also with 20 hp carb and different coils and CDI box. No affect..

 

[AlTn]

Re: 25hp Johnson-Oily slime from exhaust...

k..this will relatively painless as it's simple on your model...swap the coil and mark the known good cylinder < bottom > before swapping...now, does it run the same as it did in your post #8 < motor runs 10 sec.with upper plugwire off and stalls immediately when the lower one is disconnected > or is it now reversed? runs with lower disconnected and dies immediately with the upper one pulled?

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

I switched the coils and the problem stayed on upper cylinder. I'm going for exhaust cover, gaskets and baffle next.

 

[laujok]

Re: 25hp Johnson-Oily slime from exhaust...

Okay.. I'm totally running out of ideas. I switched a new baffle plate and gaskets, still runs the same. Looked the reeds too, didn't notice anything strange. It only runs close to normal with the idle mix screw out about a half turn, but it misses and shakes. Both plugs are wet and I tryed with Champion surface gap plugs too, still the same. Power pack is new and spark jumps 7/16" like I mentioned in previous posts.
New Ideas Anyone?
Thanks