18hp Johnson won't start stumped.

[freddyray21]

I recently bought this motor. It's a 1958 Johnson 18hp. The mice were in it and it has no spark (excellent compression). I pulled the flywheel and sandpapered the points good. Still no spark. The points, coils and condensers look brand new. I bought two new condensers and still no spark. I hate to throw parts at it so is there anyway I can test the coils with just an ohms meter. I have a manual although not the factory one, but it tells me I need a special tester to test all the components. I think if I had spark this one would run. Already replaced the impeller and lower unit lube. It's ready to run.

 

[tmcalavy]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

If the mice were in it, go over all the wires/connections with a fine-toothed comb. Then check the flywheel magnets...they can lose their juice.

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

checked all the wires. replaced the plug wires. the magnets will hold a screw driver holding the flywheel upside down.

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

bump

 

[samo_ott]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

Hmmm... that's a weird one. If you're 100% sure the coils look new and workable then pretty much it has to be in the wiring. There's not a lot of it to check though. Tradionally in the older engines it's always in the coils. Can you post a pic? I would remove the coils and look at the bottoms. I have seen some where they burned through the bottom and shorted out but the tops looked fine. But that usually happens to one side of the other, not both. As both ignition systems are independant, it's rare/weird that both are affected. It sounds like a common issue if which there is little other than the flywheel. But it's almost ALWAYS in the coils in the older engines.

p.s. the 1958's were the nicest looking engines... get it repainted! I've been looking for a '58 18HP for awhile now!

btw, I just read a post in the last few days where they stated the required primary and secondary resistance that the coils should have. Look through the old posts.

one last thought, is/was the flywheel key intact and in place? If the flywheel is not aligned, no spark.

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

I have had both coils out when putting on new plug wires and they look new all the way around. I think I might unhook the kill switch wires. I inspected them closely and did not see where the mice got to them, but who knows. It has to be something simple I have over looked.

 

[samo_ott]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

It is probably something simple if the coils look good. Keep looking. Actually I disconnected my kill wires on my 1958 10hp also. And you're sure the flywheel lines up ok?

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

the key was not out of place so I am assuming it lines up fine. I am going back to square one in the morning after I get off of work. I will check it all again.

 

[F_R]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

Do you have an ohmmeter that will accurately read less than one ohm? If so:
Check the resistance from where the wire attaches to the points. (ground other lead to the armature plate) Resistance should be zero with the points closed and less than an ohm but more than zero when the points are open. If you aren't getting the zero when closed, they aren't making good contact.

Check the resistance from the spark blug wire to ground at the armature plate. Should be several k-ohms. Infinity means bad wire connection or open secondary in the coil.

Is the breaker cam right side up? It says "top" on the top.

The magnets never go bad on those motors. They'll still be good 100 years from now.

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

I'm still not convinced there was anything wrong with the points, but I replaced them and have good spark now in both cylinders. Let's see I have good compression, spark and oh yeah fuel. I might work on that tomorrow. I think it will fire right off, but I know it will need a carb rebuild. Already got the impeller replaced. The lower unit grease was thick, but clean and no water, but in one that has set that long it may not stay that way. .

 

[crb478]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

I have found that in some engines you need to run a emory board over the surface of the points to get them clean enough to fire. I had one boat with a four cylinder I/O that I had to do this with at the beginning of every season to get it to crank.

 

[samo_ott]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

That's good you got it running? Do you know what it was specifically?

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

had already tried cleaning the points. Don't have it running yet. I still need to hook fuel to it and will probably get to that tomorrow or Sunday. The points with an ohms meter just didn't seem right so I am guess it was that.

 

[tmcalavy]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

You might want to clean the fuel system before you try to fire it up. I've done four of those models, from 56 to 62, never really knowing their previous history. I always pull and clean the carb before starting and check/replace any of the fuel hoses that seem old and brittle. Sometimes the carbs are clean, but more often than not there is some dried crud around the float/seat and in the bottom of the bowl. It'll crud up the carb passages when you put fresh gas through the system, if they aren't cruddy already. Simple carbs, easy to pull, clean and re-assemble. Work on a clean surface and lay the parts out so you know what goes where as you disassemble it. The FD Johnsons are one of the sweetest, most reliable outboards ever made. Enjoy yours after you get it running again.

 

[freddyray21]

Re: 18hp Johnson no spark testing procedures?

Re: 18hp Johnson no spark testing procedures?

will do. I need to clean out the pressure tank that came with it also. I replaced the line with new already. It seems to hold good pressure we will see. I will probably replace the pressure tank with a fuel pump if I keep this motor.

 

[freddyray21]

Re: 18hp Johnson won't start stumped.

I tagged onto this thread so you can see what I have done to this motor. First problem was no spark. I fixed that. I have good spark in both cylinders. Before even trying to start it I pulled the carb and rebuilt it. Tried to start it today and it won't start. It's not getting the gas to the cylinders. If I choke it I will get gas into the throttle body, but it doesn't seem to be getting to the plugs. I sprayed starter fluid ( I already know about starter fluid and two strokes so don't preach) into the throttle body and it would run just until the fluid ran out. I did not want to continue to try and start it this way so I left it alone. Any ideas? BTW when I picked up the motor I checked the compression and it was 120 in both cylinders. I have not rechecked as I haven't done anything to change the compression. I am running the gas a bit rich with oil probably about a 20:1 mix as it has been a while since this has run. One other thing. I took the armature plate off when I fixed the spark to run new plug wires. I suppose it is possible I have it way out of time, but it would not explain the no gas to the cylinders?