'84 Evinrude 90 stalling and coughing after de-carb treatment

[Marinebird79]

Good afternoon, this is a wonderful site with great people for help. After reading this site about decarbonizing an evinrude 90 I went and use the Sea Foam decarbonizer. I followed the instructions posted by experienced people and everything went fine. Before decarbon I do a complete carburator cleaning and put new carb kit for both carbs and do a carb sychronizing in the water, I installed new spark plugs champions QL77JC4 gapped at .30 and the motor was running fine in and out of the water.

To do the decarbon I turn on the engine to normal temp use a separate tank with the sea foam sprayed the sea foam into carburators while the motor was running, did this for about 20 min. then shut down the motor take away the spark plugs and sprayed the ramaining sea foam bottle into the spark plug holes and let it sit all night. start the engine all seafoam was consumed then use a second bottle so the engine will have a more deep cleaning. after the two decarbs I took the boat to water for a wide open throttle run and It run fine with fresh gas and the same spark plugs, take the boat to home and after two weeks I turn on the motor and it started to stall and cough from the prop exhaust after each cough it spit smoke. Check spark on all plugs and all had spark, turn on motor and disconnect each spark plug wire from coil to see if motor stalled so I can check if the coils were ok and all four were ok because the motor stalled more. I install new spark plugs, get a separate bottle with fresh gas because I suspected water in gas and turn motor but the problem still was there, when I open the trottle the engine did not accelerate like before and after I release the throttle the engine wanted to stop. I am clueless about what could happen because the engine was running fine before decarb just a little hard to crank/start maybe because of the carbon buildup but now it cranks fast but now it is stalling and coughing from the exhaust and accelerating very very rough..and while I accelerate, the engine cough/spit smoke can you help me with this problem or any ideas of what cauld be the cause. I am thinking that the carburators were affected with the seafoam or the seafoam remove dirt and the carbs get dirty any help please....thank you.....

 

[Marinebird79]

Re: '84 Evinrude 90 stalling and coughing after de-carb treatment

 

[Marinebird79]

Re: '84 Evinrude 90 stalling and coughing after de-carb treatment

I check compression on all four cylinders with spark plugs removed and open throttle, I was shocked to see 30 psi the most on all four. I do not know why this happen If seafoam is supposed to help compression go up. Motor was running great after I decarbon and run WOT on lake. return to home and sit for two weeks started engine on earmufs with new spark plugs gapped at specs. and the problem started with rough idling, couging/spitting from the exhaust after that I checked the compression and was surprised that it was 30 psi on all four. Motor does not shut off starts right after i give it a shot of premix gas direct and after it starts it idles rough coughs and spit smoke from the exhaust while accelerating/revving but the engine does not shut off it keeps running, the engine does not run hot, it have been always run normal temp and after a second test with engine warmed the compression is still 30 psi on all four and doinng the same symptoms please help me what could be the reason this happen, what should I suspect have caused the de-compression, and idling/revving rough. on lake run great/normal after decarb, but now has 30 psi on all four cylinders

 

[AlTn]

Re: '84 Evinrude 90 stalling and coughing after de-carb treatment

unlikely that 30psi is a true reading, especially since you've had it running with this reading...try another gauge...or your gauge on something else. Are you watching the gauge as you turn the motor over and this is the highest it will go?...if not, try it to ascertain that this is the case. If the readings remain that low, it's time to pull the heads and see what's going on.

 

[Marinebird79]

Re: '84 Evinrude 90 stalling and coughing after de-carb treatment

Thanks for the reply yes I have used the same gauge the one that you rent on the o'reilly autoparts it's a decent gauge but I don't know if it is good or is not calibrated, and yes I had my wife at the start key while I was reading the gauge as the motor was spinning the first try I made at the beginning I had 120 psi on the 2 right side cylinders and 30 psi on the other side at the next day I run the engine and now the 120 psi right side cylinders readed 30 psi no more with the same gauge with a cool and warm motor make no difference. I was shocked/shaking that all four were 30 psi and engine making same running symptoms

Today before I started the engine I noticed some black carbon dirt on both side lower cylinders between the block and head just in the middle where the gasket is and both in the same place but I could not notice any water leaking or any exhaust sound or fumes coming out from there even with the motor running at normal temp, I pulled out the lower spark plugs and noticed that they were very clean with a light tan oily and liquid residue almost like if they were cleaned after I pulled the top ones they were darker and don't have liquid oily residue they had just dark moist residue sticked. I also noticed very few little shiny metal dirt on the lower spark plugs and very very tiny droplets like water, and on top of the two lower pistons that I could noticed through the spark plug hole I am afraid that after the two decarbon treatment I had broke the piston rings

I know I would have to pull the heads, but I want some expert advise of what can be the reason before doing this

Could that be one reason that the Sea Foam did this...?
Do I have both blown gaskets......?
Can water inside the cylinder make engine run like this or is because of the low compression or both....?
If the rings are broken does the motor make a sound...?
A broken gasket can cause all cylinders to have low compression or just to one cylinder?
When I stick my finger in the spark plug hole and turn the flywheel the piston sucks air and then release air to te point that I have to apply pressure to keep the finger in.

Can anyone advise me now that I have a more descriptive situation...Thanks