1984 Johnson 40hp running wierd

[racerone]

If spark can jump a gap on the sparkplug then a poor connection inside the sparkplug boot means nothing.----Know of a 2008 optimax with low compression on one cylinder---Owner still looking for a shop that will take the job on.----Says he is going to try to fix it at home.

 

[oldboat1]

think it would follow then, that getting the wire half an inch or so from the spring connector would be good enough. or getting the plug 1/4 to 1/2" from the connector would be enough -- or getting the coil spike within 1/2" from the wire. That doesn't seem right, R. Thinking in the case of the spring to plug connection, loss of full connectivity would be enough to weaken the spark to the point it wouldn't fire. [edit. Make that intermittent spark or no spark, not weaker.]

edit. that optimax -- shop wouldn't routinely take a job like that? we gotten to a point where 2008 outboards are disposable?? geez.

 

[pikelucius]

Now that I think of it, I did pull all the connections and grease them before I walked away to do research. I didn't think anything of it being as the plugs were all tight and prongs were clean. Could all of this have been a less than perfect connection to either the CDI or charging coil? Its hard to believe it could have been something so simple.

I wish 2008 outboards wer​e disposable. Nobody is selling fuel injected outboards private party yet, and dealer want an arm and a leg plus the price of a new boat, and they may or may not honor a warranty.

 

[oldboat1]

Yeah. always headslappers. I would think the pin and socket connections are less prone to issues than plug wire connections (spring connectors and such -- maybe the plug wires themselves). As your recent fix apparently had to do with plug wires, guess that would be the first place to look if you have repeated problems out on the water (hope you don't). Those CD ignitions put out a powerful charge, like Racerone is saying. Good to take a pair of work gloves along when you go out for a test run.

Interesting about private sales of injection outboards (or lack of them) -- didn't know that. Guess the market will catch up sooner or later.

 

[pikelucius]

I still think it's strange. If it continues, I'm still thinking the CDI is suspect. I wish I would get shocked, then I would know the problem. I might make up some new plug wires just for the heck of it. I do it to my truck, why not the boat.

 

[jrttoday]

maybe a stupid question? Have you used this site http://issuu.com/cdielectronics/docs/troubleshootingguide ?

 

[oldboat1]

Easy fix or maintenance (wires). Should be standard 7mm -- solid wire core. If in the States, try NAPA. Think I would try running a little first, though know first hand that intermittent connections/shorting of any kind are a pain. If you have the coin and plan on keeping the motor, a new CD unit gives you one for a spare (did that this summer, more by mistake than intentional, though). Alternatively, might replace both the charge coil and sensor for a little less -- if switching out parts.

Rather than getting a poke checking for dropped cylinders, might consider a timing gun (newer self powered variety handier). I use an old 12v gun for that, once in a while -- a lot easier when reaching over the transom (just clamp onto a plug wire to at least see if the coil is firing).

 

[pikelucius]

I already put a timing light on it. That's why it's so confusing. I have better than average compression, a brand new fuel system, bright spark when I checked, and it is in time. Yet it ran weird. It has to be intermittent weak spark. If it was only when hot, I would think coils. It has to be either CDI, charging coil, sensor or the flywheel. I just replaced CDI last fall, and they are over a hundred bucks. If "outboard" sparkplug wire isn't anything special, I still have some 7mm automotive wire and terminals around somewhere. Actually the coil prong looks like a distributer terminal will work.

The only other thing is one time was a dirtbike that had a very similar problem. It had fuel, it had spark, and it had good compression. It turned out. A piece of the piston skirt broke off. How, and where it went is still a mystery. That bike still runs after a rebuild, so it didn't get to the bottom end. I couldn't find it in the pipe either. But when it happened, it was sudden, and wouldn't idle at all. Actually, aside from idle, it still ran great!

I'm going to the lake now.

 

[pikelucius]

I took it out on the lake, and it is running absolutely perfect. It still scares me that I didn't really do anything to fix it, and the problem could certainly come back. I'll keep it local for now, but in the future I'd like to take it on bigger waters. Its no fun to putt back 15 miles from shore.

 

[oldboat1]

but you did fix it. Know what you mean about uncertainty, though.

Maybe a get-me-home motor. I'm a big believer in those.

 

[pikelucius]

The one thing I can't argue, is this is one bad-*** motor. Twin cylinder with dual carbs, a loud thumping idle, and a growl like no other. Everyone always comments how it sounds mean, and it sure does smell nice with Penzoil full synthetic.

 

[oldboat1]

yup. have an '84 Mercedes that's a little like that, or guess it would be like that if I burned veggie oil (noisy and smelling good).