gotta miss

[Itec01]

Hi all,<br /><br />I recently bought a 1959 18hp Johnson Seahorse.<br />The previous owner had said it ran fine and had taken it for a short ride. It had been sitting for 3 years.<br />I took it for a ride and it slowly began to lose power and is now running at about 40% of what it had a week ago.<br />He said he cleane the gas tank with air pressure and did not get all the crud out because I found more. I pulled the carb and cleaned everything. Points look great, has good compression, and I put a new pick up tube in the gas tank, and cleaned that also. Has good spark. The motor idles fine. When I give it full throttle I get weak power and when I slow way down I get a back fire through the air intake.The top cylinder seems to be running hotter than lower one. Any suggestions or is this motor ready for the motor doctor.<br /><br />Thanks to all who have helped me out.

 

[Yepblaze]

Re: gotta miss

"Points look great" <br /><br />Did you run a piece of paper through them making sure there was absolutely no residue or piting? Also heard the coils will go bad from age and might show signs of the plastic cracking.<br /><br />Are you using lots of oil in the premix with fresh gas?

 

[Itec01]

Re: gotta miss

Points look new. I did not do anything with points. Just looked to see if thwey were old and pitted which they were not.<br /><br /> About the coils. I think it may be something in the electical end of it all.<br /><br />I'm using a 24:1 mix with fresh gas.

 

[dicktaber]

Re: gotta miss

Okay, take this with a big grain of salt cause I'm NOT an outboard expert, but...if this is a reed valve motor, and you're getting backfire thru the intake, I'm thinking reed valve problem (probably on the cylinder that's running hot). Help me out you old OMC guys...am I way off track?

 

[oldboat1]

Re: gotta miss

Slow loss of power doesn't sound like a coil, but can't rule it out either. Unless your model has a peep hole in the top of the flywheel, you have to take off the flywheel to get at the coils. If there is any indication of cracking or splitting, just replace them -- In fact, might just replace them anyway while you are in there. You can get coils for your model at NAPA, or from dealers (the latter a little more expensive). And when you are under there, you might as well replace the points and gap them properly. Then replace the plugs.<br /><br />If you would like to rule out fuel problems first (not unreasonable), start with fresh gas and oil (TCW-3 oil in a 30:1 or 40:1 should work -- 24:1 if you want to start there, but use a small amt of mixed fuel to begin with so you don't waste it while trying to get the motor up and running. If you have too rich a mix, you will have trouble keeping it running.) If you are running with a two-line pressure tank, you need to make sure that there are no air leaks -- old hoses and leaks at connection points are the usual problems.<br /><br />lots of possiblities....