Re: 1987 Johnson 15 HP Hard Re-Start
Since the engine is just recently purchased, we will have to assume you have no maint history on the engine....if you do, please share.<br /><br />There was two different carbs with this engine, an early model with a rounded top carb and a late model carb with a flat top covered by a black "plastic" cover. Both had the same cam follower roller.<br /><br />Usually, with this type of problem on these particular engines, it's carb related. If you have no idea when the carb was overhauled last, this would be a good time to do it. Also, look at the cam follower roller. The rollers from that time had a plastic insert that would eventually crack and fall off. If the insert is is missing or there is a deep groove in it, replace it. The PN is 323328.<br /><br />If all the above is OK, try this....if you have the early production carb, run the low speed needle in till it's GENTLY seated and then back out 1 1/2 turns. Run the engine till it's up to temp and then adjust the needle for best idle IN GEAR UNDER WAY on the boat.<br /><br />If you have the late production model carb, again run the low speed needle in till it's GENTLY SEATED and then back out 2 1/2 turns. Then adjust for best idle as stated above.<br /><br />But before you do any adjustment, rebuild the carb....stripping it down and soaking it out good and then follow up with compressed air to blow out all the passages. Carb kits are availabe through your local John/Rude dealer.<br /><br />Some other questions.....is the engine running at a normal temp? After idleing for a while, can you touch the flat place on top of the block just forward of the head? If you can lay your fingers there for several seconds, the engine should be running at a good temp. If it's cold and does not warm up, either the t-stat is stuck open or not there. The engine needs to run at the correct temp for good service.<br /><br />The spark on each cylinder should jump a 1/2" gap with a strong lighting like spark. This would ask the question....how did you check the spark?<br /><br />If you can add any thing to your previous post, please do. We can help....just need info....
<br /><br />Edit: Compression readings on each cylinder would be a good idea also. In the 90's on each cylinder is great....more important is that each cylinder is within 10 to 15% of each other on compression readings.
