powerpac ? 1979 70hp

i went to the river today and my 1979 70hp johnson was only running on one cylinder.when i got home and checked it out it was running on all three.the only thing i found was one ignition coil is leaking.I am thinking power pac.what do you think?

Re: powerpac ?

In your case, a failed powerpack isn't likely. I've yet to see one of those type packs to be intermitent. It's always been a case whre if the pack was bad, it stays that way.

Are you using Champion QL77JC4 plugs gapped at .040 ? If not, do so and if you're lucky, that might cure the problem.

Also.... if you have a tachometer and it's been acting up or not working at all, possibly the rectifier has failed for some reason. This would allow voltage to back up at the stator (beginning of charging and ignition system) which would cause the stator to overheat and start to melt down. This in turn would result in a voltage drop from the stator to the powerpack..... resulting in weak, erratic, and evntually no ignition (spark).

Check that stator (under the flywheel) to see if there's a substance dripping down on the timer base and powerhead area, and if so, replace the stator.

Re: powerpac ?

thanks for the info. will check and get back to you.

Re: powerpac ?

i have had the shellac or whatever these coils are covered with crack with age and allow moisture to get to the coils...the things then dry out and work ok...i think a coat of varnish would have fixed the problem but i dumped the boat and engine for other reasons...

Re: powerpac ?

Papyson.... Dumping the engine (or replacing the stator) would be the right move. Varnish wouldn't have helped.

Re: powerpac ?

you right Joe....there was several issues with that motor....bought it used and top piston went within a year...was used motor....should have dumped it then....i have been away from the forum for a while and just returned....looks like you are spending a lot of time in here..thats good and i will say thank you for all the people you have/are/will helped....Carl

Re: powerpac ?

lstring...... More possibilities.

1 - Find the black/yellow wire that leads from the engine wiring harness to the powerpack and disconnect it. Hook a ammeter or a volt meter set to its lowest DC voltage reading between that harness black/yellow wire and any powerhead ground. Turn the key to the ON position (engine NOT running). If even a microvolt registers on the meter, replace the ignition switch as that indicates a shorted switch.

Any battery voltage applied to that black/yellow wire will destroy a powerpack within a very short time.

2 - Even if no voltage is detected at that black/yellow wire, the ignition switch may still be at fault. This can be found simply by leaving that black/yellow wire disconnected from the powerpack and test run the engine. If the problem is not non existent and the engine runs and runs and that problem does not reoccur..... the ignition switch has a non voltage short to ground, in which case replace it.