90 2 Stroke Johnson idling rough and cutting off at idling

I have a 2 stroke 90 Johnson 2003 model. When I put it in the water the engine on idling will not run smooth and then will cut off. When I crack it back up it cracks fine but I have to give it some gas to get it going and not cut off on me. If I run the engine hard for 5 or 10 minutes and then go to idling speed it does just fine. It runs great, but when I cut the engine off and let it set for 30 minutes or so and start it back up it we are back to square one again. (Cutting off at idling speed and have to give it alot of gas for it to run. I did have my boat machanic look at it and we replaced the hoses, bulb, water pump and themostates. After replaceing the water pump it doesn't push out as much of water as it did before we replaced the water pump. Is this common for this type of engine.

Any suggestions on what might be wrong with the at idling speed would be appreciated. The engine doesn't stop at idling when I have the ear muffs on it in my driveway. Thanks for any help in advance.

Lee

Re: 90 2 Stroke Johnson idling rough and cutting off at idling

i just went thru something similar. check the plugs for water droplets. check compression on all cylinders. may have a bad head gasket. this was about the exact description of my problem.

Re: 90 2 Stroke Johnson idling rough and cutting off at idling

What did you find out the problem to your engine was? Was it a blown head gaket and what did you do to fix it? Thanks for your help!

Re: 90 2 Stroke Johnson idling rough and cutting off at idling

OK. well first i noticed water on the spark plug from the middle cylinder. so i checked the compression top was 140 middle was 70 and bottom was 140. so i pulled the therm cover (pic 1 ) water cover ( pic 2) and head ( pic 3). Found a breech in the head gasket between cylinder 2 and 3. this was causing the water to get into the cylinder and low compression. this is what caused the engine to run so rough. i ordered new gaskets for the thermo cover, thermo, water cover, and head gasket. also ordered a new thermostat. all the parts were 54 dollars, and i took the head to a machine shop and had it resurfaced for $55. plus this gave me about 5 extra hp. total cost was about $110. i got my parts in 4 days and got the head back in 1 day. First thing i would do is check the compression. If compression is about equal, then i would check the carbs. These are easy to do, i would do this myself and skip the mechanic. i see yall already rebuilt, It is possible that the low speed screw was not adjusted properly on one or all of the carbs. or there could be trash in a jet. compression test will definately let ya know if it is a head though. and ya can probably buy A compression tester cheaper than you can have a mechanic check it. but there is a chance he would check it for free