1969 johnson 25hp outboard no spark

[dvie12]

please refer to previous post http://forums.iboats.com/showthread.php?t=510947



was a good video and answered some questions but still have no spark coils check good replaced the plug wires even though the showed good continuity new points and condensers set points at .020 and new spark plugs the coils are lined up with the machined surface at the end of the coil pick ups so i assume the air gap is correct for the magnet in the flywheel what next

did a compression test and got 100 0n top and 95 on the bottom cylinder

 

[Daviet]

Re: 1969 johnson 25hp outboard no spark

Try disconnecting the the black shorting switch wires and see if you get spark.

 

[dvie12]

Re: 1969 johnson 25hp outboard no spark

they are disconected

 

[F_R]

Re: 1969 johnson 25hp outboard no spark

Assuming your coils look good with no cracks, 90% of no-spark problems on those motors is due to breaker points. Most of those problems are because they are dirty or not making contact when closed. Other problems come from contamination with oil, or crud.

"Looking good" is not a good test. Clean them. I reccommend taking them apart and polish each contact shiny bright with 400 grit wet-or-dry sandpaper. Yes, .020" is the proper gap when reassembling.

Other possible scenarios are coil wires connected to the wrong breaker sets, cam upside down, improperly routed wires worn through and grounding out, etc.

You said your coil primary ohms out at zero. That is not correct, they should be about an ohm. Of course it takes a pretty good meter to distinguish the difference. Nevertheless, I seriously doubt that is your problem. The primary rarely goes bad, especially on both coils at the same time. Secondary should be several k-ohms.

The breaker points SHOULD ohm at zero when closed, and infinity when open (wires disconnected). Again, it takes a good instrument to tell the difference between zero and a couple of ohms. It won't spark with a couple of ohms resistance across the points.

 

[dvie12]

Re: 1969 johnson 25hp outboard no spark

the points and condensers are new i will check continuity with them closed and open will also give them and the base the mount on a polishing
i got an analog meter (was using a digital) and retested the coils 0 ohms primary and 9000 ohms secondary checked secondary from spark plug connection to the ground wire on the coil just to be sure the plug wire was connected to the coil and the plug terminal was making good contact in the plug wire it is the kind that pins into the plug wire and the boot slides over it both coils checked the same

as far as the coils being connected to the wrong points it is wired with the front coil as you face the engine from the pull rope end to the right side points and the rear coil to the left side points green wires to points and black wire to the top of the coil

the cam is on correct i assume because it has a stamp on it that says top and that is were i have been setting and or checking point gap

the wiring is routed clear of moving stuff and isn't pinched anywhere checked all of that at the beginning

thanks for the info will check it out asap and let you know

 

[mark in new jersey]

Re: 1969 johnson 25hp outboard no spark

"Looking good" is not a good test. Clean them. I reccommend taking them apart and polish each contact shiny bright with 400 grit wet-or-dry sandpaper. Yes, .020" is the proper gap when reassembling.

It is with great trepidation that I, a lowly cadet, take exception to anything said by a Supreme Mariner, but electrical contacts are something with which I have a lot of experience via an engineering position I held at a previous day job.....

Sandpaper....or emery, or any such abrasive....is made of silica. Silica is an insulator. As such, using sandpaper to clean electrical contacts is considered a no-no, as doing so can (and usually does) embed silica into the contact surface. In your attempt to make the contacts "conduct better", you're pressing microscopic insulators into the contact's surface.

Contact cleaner + steel wool is vastly superior.....just blow them clean with compressed air afterwards.

 

[dvie12]

Re: 1969 johnson 25hp outboard no spark

the points are new and i didn't mess with them but i did clean the mounting surface they sit on tested resistance before and had about 1.5 ohms (read one and one half ohms) no spark

after cleaning the mounting surface i had .03 ohms (that's 3/100 of one ohm) the motor now runs went ahead and rebuilt the carb was pretty gunky inside.

haven't ran it more than just the few moments to know it ran, need to know the torque for the flywheel it would be greatly appreciated i cinched it down pretty good but i know it needs to be properly tightened before really running the motor

one other question, is the fuel pump serviceable beyond cleaning or replacing the filter can it be rebuilt

thanks for all your help hope this helps others out also

 

[kfa4303]

Re: 1969 johnson 25hp outboard no spark

Hi dvie12. Glad you got her running. Unfortunately, many of the the fuel pumps don't have rebuild kits. I don't see one listed here at iboats. About all you can do is clean the screen like you said. That being said, the pumps are usually pretty tough and don't often fail. Do you know it's bad for sure? If you can squeeze the primer bulb and it gets and stays hard, with the motor off, then the pump is probably ok. If you have to manually pump the bulb to keep it running, then the pump is probably not good. If you do need another pump you might want to try to get one off of a donor motor. A new replacement pump is about $55 :/ Hope that helps.

 

[AlTn]

Re: 1969 johnson 25hp outboard no spark

45 to 50 ft/lbs for the f/w torque

 

[dvie12]

Re: 1969 johnson 25hp outboard no spark

thanks for the info haven't had a chance to get back to the motor will let you all know how it goes again thanks for all the help