first time decarb on 1990 evinrude 120

i went to the shop yesterday to get a can of engine tuner.the mechanic sold me a preventive maintenance valve to replace the other and a injection can to hook it up to he said it was much easier doing it this way instead of trying to squirt it into each carb.it says to run motor to normal operating temp then run motor at idle and give one 2 second burts for each cylinder waiting 2 seconds between burts.then give it a 20 second burst or when engine stalls.then let it soak for 3 to 16 hours.then run motor at fast idle 1500 rpms for 15 minutes and repeat the procedure if necessary.has anyone did this before or have any pointers i have never did it to this motor before.is the maintenance valve the easier way to go.he says i can fog my motor thru this valve too.i would appreciate any helpful hints.<br />thank you<br />scott

Re: first time decarb on 1990 evinrude 120

the port is an easy way to fog or decarb your engine. i fogged my engine at the end of the season using the method you described. lots of black smoke, but it finally stalled and went to bed for the winter. this spring, i couldn't find the engine tuner with the port, so i went with spraying it in the carbs. wasn't any harder, just different. white smoke this time. once it sits after a time period, i'd forget the fast idle and go run it for a good half hour to get that stuff out. i'm a novice and this was easy. good luck-

Re: first time decarb on 1990 evinrude 120

thanks matt.do you decarb your motor yearly?

Re: first time decarb on 1990 evinrude 120

I have a 1990 Johnson 120. Is decarbing something you MUST do or is it done to fix a problem. Is it possible that it will make things worse if I decarb my engine? Could the compression drop? I have had this engine for 3 years and I have not done it, but it runs just fine. I have always felt that if it ain't broken, don't fix it.

Re: first time decarb on 1990 evinrude 120

i plan to decarb the engine yearly, but i also plan to run it a lot. i think most products recommend decarbing every 50 hours, but you could probably go higher and be fine.<br /><br />is it something you have to do? i don't really know. can it hurt the engine? i seriously doubt it, many do it and many companies sell the product. the concept makes sense to me, and i saw all sorts of black gunk come out of my engine when i did it, so i will continue to do it yearly in the spring.