engine miss

[paul115]

hello- i have a 1985 johnson 115 horse outboard jet-bought it new and it has never failed me until yesterday- it started to miss on one cylinder-i pulled all the plugs and one had the electode tip pushed up against the bottom of the plug-i inspected the top of the piston and what i could see of the cylinder and it looked good- i took an compression test and they all came out about 100lbs. except the one that was missing and it had 95-i replaced all the plugs and fired it up for a little bit an it ran fine- should i take it in and have it tore down? or run it ? any suggestions will be appreciated.<br />thanks <br />paul

 

[wayne h]

Re: engine miss

the 95 is alittle low but still within the 10 psi drop.i would not worry about it.i would decarb the engine and take another compression test .it sounds to me like the engine might be carboned up have you ever decarb it ?

 

[RVAHA]

Re: engine miss

I had this happen to me on my 175 Johnson '79. I regapped and checked it later with the same results. I did a preliminary check by poking a screwdriver threw the spark plug hole and noticed some play in the piston. I pulled the head and found that the piston had been hitting the head. Hopefully this is not your problem, but pulling the head should give you an idea.

 

[paul115]

Re: engine miss

thanks wayne and rick for the reply- the piston feels tight with no play-think i will try the decarb first-what is the best way to decarb?<br /><br />thanks<br /><br />paul

 

[paul115]

Re: engine miss

thanks wayne- decarbed and went up the river at 40mph-ran fine <br /><br />paul