Re: 6hp 1966 johnson outboard
thanks cajun,
Well this motor is new to me, i have had it out fishing twice and found it does the same thing both times. This motor sat for ten years in a boathouse, in dry conditions he told me. As far as he could remember it always did that sputtering and missing and jerking then cut out thing on low idle. Is the crankcase in these old motors '60-'66? poured brass with no bearings? dont they tend to get out of shape in someway, which cant be fixed?
Well, it seems that this motor has sat up for a while before you acquired her. At this point I don't think there is a crank seal problem, unless you notice oil coming out of the seal area.
Your
carburetor probably has not been cleaned in years and maybe before it was put up in the boat house. Would consider cleaning the carb with a kit. Read the machinist article about 6hp motors, he has an excellent section on how to do that.
If your curious, here is a break down of your power head and the crankcase.
http://www.boats.net/parts/search/BRP/EVINRUDE/1969/6902M 1969/POWERHEAD GROUP/parts.html
Since you motor has sat up a while, it will be good if you read this article about
waking up a sleeping outboard. Some of the things you probably have already done.
http://forums.iboats.com/showthread.php?t=158086
If you haven't had your impeller or waterpump replaced, then I highly suggest replacing that thing, even though is currently pumping water. It is pumping water, right? After all those years they can just break apart while running and the owner not know it until the motor overheats and seizes up and cause damage to the cylinders and pistons.
Have you check the compression on your motor? Poor/low compression or compression on each cylinder with a 10% difference on a motor can cause poor functioning/running. Low compression can come from blown head gasket from overheating to damage pistons or cylinders.
Here is a link to tell how to check your compression. Hopfully your numbers will be high 60's to 90's PSI.
http://forums.iboats.com/showthread.php?t=313963&highlight=compression
I would make sure those spark plugs are gapped at 0.030
A good way to assess a problem with a no running or poor running motor.
You will see a lot of experience guys ask about compression, spark and fuel. (They are using a systematic approach to diagnosing an engine problem or problems....in this order)
C= compression ( if your compression is low are uneven between cylinders >10% then others checks don't matter until the that is resolved)
S= Spark (if your having problems with your ignition then you can have the cleanest carb and great fuel delivery but it will run bad or not at all)
F= Fuel (if your carbs are not clean and fast/slow idle needle are not set right then it will run but like crap. If you have it set too lean then you run the risk of poor fuel/oil delivery and damage your pistons and cylinders then you run into the problem of C (poor compression from damage).
Check out the forums secret file area, a lot of excellent reading and a huge thanks to all the guys that took the time to put it together.
http://forums.iboats.com/showthread.php?t=299680
http://forums.iboats.com/forumdisplay.php?f=31
Hope this information helps you out. Will be out of touch for about 3 day or so, but if you have more questions or problems, please post and hopefully one of the experience guys will chime in to help you out. Good luck.
cajuncook1