Blown Powerpulse? Tragic Accident.. please help

[NijkampTO]

We just bought a boat with 1968 Johnson 100 HP V4 engine.
At first we had problems with no firing and only 2 sparks working correctly and one being weak and one not sparking at all..
Since we had a dead battery we decided to jump start it with the car and accidently connected the car battery the wrong way.. then the boat battery started smoking and we disconnected it again.. stupid mistake we know..

Now we don't get any sparks.. the starter and everything still works though.

Did we fry the powerpulse? I tested the stator before this accident and it had 0 ohms.. maybe I did something wrong.. either way we had sparks before the accident and now none.

What and how do we need to test and replace?

Thanks

 

[F_R]

Re: Blown Powerpulse? Tragic Accident.. please help

For sure, you blew the charging system. And possibly the pulse pack. You test it either with the proper equipment (DVA meter) or by eliminating everything else. Expensive mistake. But I guess you already knew that.

The service manual won't tell you how to test it with a DVA meter. They weren't in use back then.

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

I'm assuming the charging system includes the stator and rectifier?

Shouldn't I still get sparks without the charging system meaning the powerpulse is broken for sure? Or no?

How about the battery, it still lights the bulb and turns the starter.. should it be ok?

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

Could the pulse transformer or distributor have gotten damaged too?
I'd like to see what would need to be replaced to see whether it's better to pick up another engine for $400 somewhere or fix it..
The engine ran good for a while then suddenly stopped.. couldn't get it to start anymore (outruled overheat). Mechanic said only 3 plugs spark. Now none spark.

What parts need to work to get a spark? How can I test them?

 

[F_R]

Re: Blown Powerpulse? Tragic Accident.. please help

Reversing the battery would not damage the transformer or distributor.

You need 12V input to the pulse pack, and a signal from the sensor under the flywheel to tell it when to fire. The output from the pulse pack goes to the transformer (coil). The output from the transformer goes to the distributor, which directs it to the proper spark plug.

A voltage suppressor clips off harmful voltage spikes that might damage the pulse pack.

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

**It looks like the voltage suppressor is missing, the previous owner put in a new powerpulse and might have removed the suppressor by accident..
Boats.net wants $130 for the suppressor.. do I really need it if I stay careful with the battery in the future?

Note that we did not reverse the battery, but instead we hooked up a car battery in reverse to the boat battery which is hooked up properly..not sure what the end outcome of that is..

Should I expect the powerpulse to have broken? How about the rectifier?

And I guess the powerpulse is connected to the battery so the stator is not currently an issue.. although it could have been the cause why our engine died in the middle of the lake and couldn't restart it, right?

Thanks!!

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

What's the best way to test the powerpulse and the ignition coil?
I'm guessing with a DVA and seeing what the voltage peaks at.. right? Might have to cut the rubber around the cable to get the meter hooked up or how else could I do it?

My big concern is still, do I need the stator and rectifier on this engine to spark or not? I'm really thinking on this model that the Powerpulse is hooked up to the battery and the rectifier.. does that make sense?

Thanks! Any help is appreciated!

 

[trendsetter240]

Re: Blown Powerpulse? Tragic Accident.. please help

My big concern is still, do I need the stator and rectifier on this engine to spark or not? I'm really thinking on this model that the Powerpulse is hooked up to the battery and the rectifier.. does that make sense?

Yes you need the stator for spark.

Before deciding whether or not to put money in to this motor I would test the compression on all cylinders first. If the engine doesn't have good compression readings then fixing the electrical is not a good investment.

Personally I do not put much time or effort in to these old motors. There are just too many cheaper options available from the 80's and 90's with better technology, bettery fuel economy and parts availability.

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

Why do I need the stator to spark?

Doesn't the powerpulse get power from the battery and creates high voltage with the coil to make sparks?

The mechanic said the compressions in the 80's, all around equal (he tested it cold since he couldn't get it to start) . The previous owner said they're all around 100, and those numbers are written on the engine. The engine's been sitting for 3 years and needs decarbonized. It worked great for 10 minutes and the boat went pretty fast, not even WOT.

Used motors from the 80's and 90's run around $700-2000 here on craigslist. I can get most the parts for this motor from different websites for good prices. Fuel shouldn't be much of a problem since we won't use the boat too much. Engine ran great when it ran, just need it to run again for 2-3 years then we're selling the boat.

I'm thinking power pulse is bad $250, stator $45, rectifier $40.. that should do it unless the distributor has problems.

Could somebody please clarify and explain why I need a working stator to get sparks, when the powerpulse is actually creating the high voltage from 12 volts(battery)?

 

[trendsetter240]

Re: Blown Powerpulse? Tragic Accident.. please help

Ok, so the motor has good compression, it sounds like it's worth saving. All I was saying was to check that first.

Now, I'm not familiar with the powerpulse that is on that motor. The purpose of the stator is to generate AC power when the flywheel rotates magnets around it. In a standard stator + trigger assembly the stator is required to produce a spark.

In your case it may be that the powerpulse creates the spark off the battery and the stator is used only to send power to the rectifier which creates DC output to charge the battery.

Again, I'm not certain with that setup, hopefully someone more familiar with those older motors can chime in with specifics.

Cheers

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

That's what the mechanic we took it to thought too, but after researching and thinking about it, it turns out the the power pulse creates sparks off 12 volts, which I think it gets from the battery. The mechanic even put the carb cover on upside down.. so he wasn't much help.

I'll attach an engine diagram I made, I hope somebody can confirm it, so I can at least rule out the stator and rectifier with my no spark condition. That'd leave just the powerpule and transformer, and possibly the distributor, which worked(at least for 3 cylinders) just a few days ago.

Does anybody know more about these 1968 Johnson 100 HP Sea Horse/Meteor engines?

 

[NijkampTO]

Re: Blown Powerpulse? Tragic Accident.. please help

Could somebody that knows this motor confirm the electricity system diagram I drew?