Lost Spark.....

Was out over the weekend with my 1994 Johnson 50/35 jet. Was running fine the first few hours, then I took off, got on plane and all of a sudden it bogged out. Couldn't get over 3200 rpm's. Got home compression tested great (150 top, 149 bottom), tested spark and couldn't get spark on bottom cylinder, AHHA!! Swapped plug wires a few different ways, and it seems the bottom coil main is the problem. Proceeded to test ignition coil and got .4 -.5 ohms on primary resistance (coil main to ground), should be .1 (+-.05). Got this reading on both mains. Secondary resistance tested fine. But I think I have a problem with my ohmeter. Set to test at 200 ohms when I touch the black and red leads together it reads .3 ohms. Shouldn't that read 0? If so, then minus .3 from the readings I'm getting would give me .1 - .2, seemingly within specs. Also if I'm not getting spark on just the bottom cylinder, why would both top and bottom coil mains read the same? Wouldn't the bottom read different? I'm a bit confused.

Sooooooo, do I have a bad coil? If not, what should be my next test? Power pack? If so, I'm not sure how to test that.

Thanks for any help/insight into this problem!!!

Swap both the primary and secondary leads. This will, in effect, use the top coil for the bottom spark plug and vice versa.
See if the problem follows the coil or follows the primary wire from the power pack.
If you find that it follows the primary wire then it will either be the timer base under the flywheel or the power pack. The charge coil is apparently working.

[url=https://www.tinboats.net/forum/viewtopic.php?p=357703#p357703 said:

Pappy » 52 minutes ago[/url]"]Swap both the primary and secondary leads. This will, in effect, use the top coil for the bottom spark plug and vice versa.
See if the problem follows the coil or follows the primary wire from the power pack.
If you find that it follows the primary wire then it will either be the timer base under the flywheel or the power pack. The charge coil is apparently working.

Click to expand...

Thanks Pappy!! What I did was swap the plug wires from top to bottom and visa versa, just on the coil. Got spark on bottom, but not on top then. Also did the same on the plug end (leaving them plugged in correctly on the coil), same result. I did not swap the wires coming from power pack to coil. is this what your saying I should do?

How do I test either of those?

Yes, that is what I am saying.
Unless you have the proper tester (Peak reading voltmeter) you wont be able to test the pack. You either take it in for testing or guess and replace. Your choice.

[url=https://www.tinboats.net/forum/viewtopic.php?p=357788#p357788 said:

Pappy » Today, 7:03 pm[/url]"]Yes, that is what I am saying.
Unless you have the proper tester (Peak reading voltmeter) you wont be able to test the pack. You either take it in for testing or guess and replace. Your choice.

Click to expand...

Thanks again!!

I tested the spark again tonight with the procedure you described. Still got spark on the top cylinder, but got some on the bottom cylinder. I'm testing with a type of spark tester that you put inline from plug to plug wire. It has a small light in it that shows spark. I say I got some on the bottom cylinder because the light was flashing, but very dimly compared to the top cylinder. Put everything back together the way it's supposed to go and got zero spark from the bottom, but the same strong spark on top. What do you think?

By the way, when testing tonight I got a pretty good back fire from the engine. Very loud, and shot a bit of flame and air out of the exhaust. To be expected with me doing all of this spark testing the last two days?

Yes you do subtract the meter lead resistance when you measure. Swapped coils and problem stayed on bottom. Swap CDI and I bet it changes. Tip if you need a CDI. If the aftermarket makes it then OMC will often as they did on my 60 match the price. Get a factory one or in my opinion if you go aftermarket then change them both so they match. With all this swapping you did swap high voltage spark plug wire right?

Stumpalump said:

Yes you do subtract the meter lead resistance when you measure. Swapped coils and problem stayed on bottom. Swap CDI and I bet it changes. Tip if you need a CDI. If the aftermarket makes it then OMC will often as they did on my 60 match the price. Get a factory one or in my opinion if you go aftermarket then change them both so they match. With all this swapping you did swap high voltage spark plug wire right?

Click to expand...

Thanks!! But I'm a bit confused. Not sure what you a cdi is, or what you mean by swapping high voltage spark plug wire?

Just bumping this back to the top.

Any other insight on this issue? It seems kind of weird that I was able to get "some" spark on the bottom cylinder when I swapped both primary and secondary leads as Pappy instructed. Top cylinder was WAY stronger though. Kind of getting me confused.

Another guy on here has the same motor as me. He's willing to let me slap on his power pack to see if that gets spark back to both cylinders. Sound like a good plan of action?

[url=https://www.tinboats.net/forum/viewtopic.php?p=358004#p358004 said:

Another guy on here has the same motor as me. He's willing to let me slap on his power pack to see if that gets spark back to both cylinders. Sound like a good plan of action?

Click to expand...

That's what the pros do when they can't figure it out. Start replacing things that make sense until the problem goes away.

I don't know if this is encouraging or not, but coils do not typically just get weak. They either work, or they don't. If it were me I would probably question the wires/caps.

Thanks Jethro!!

You're thinking plug wires? What do you mean by caps?

Some motors will have plain rubber boots on the plug wire and some will have caps.

Example of cap: https://www.jpcycles.com/product/3800380?utm_source=none&utm_term=adwords_labels%3DParts%20and%20adwords_labels%3DElectrical&device=c&network=g&matchtype=&gclid=CLfljYWatr8CFUEF7AodwBEAug

Thanks!!

Mine just has plain rubber boots. Thinking about replacing both plug wires to see if that gets me anywhere.

Still have yet to confirm my power pack is the issue, but pretty sure that is the case. Going to do a little more testing this evening before I spend the $ on a new power pack.

Here is something I forgot to mention. We had lighting strike several trees in our back yard a few weeks ago. Took out our TV, surround sound and cable box. I also had my on board charger plugged in and it killed the bank that goes to my starting battery. Nothing seemed to be effected in other than that bank. The fuse going from charger to battery was still good even. Got the charger replaced and reinstalled without issue. But I notice now that when I have the key in the "on" position and push for choke I get interference in my stereo speakers, even when they are off. Just a slight "pop" that coincides with the push of the key. Any coorelation to this and the problem I'm having? FWIW after all of this the boat ran fine for about 45 minutes to an hour between 2 trips before I lost spark on the bottom cylinder.

Timer base seemed to ohm out OK, from what i could tell. Went ahead and ordered a new power pack this evening. Hoping that's the problem!!! [-o<

Power pack to be delivered today. Fingers crossed that it fixes my issues!!!!! [-o<

Installed new power pack last night. Tested spark and got it back on both cylinders. Took the boat out for a spin and it is running great.

Thanks for all the help!!!!!!