About power packs......

[papachaz]

a question for you guru's out there. 1979 Johnson 115. dropping #1 cylinder. I've changed the coils around, after testing spark at 7/16" gap on the tester and it seemed weak. I changed it out with the #2 cylinder, but in doing so, I found the paint preventing a good ground. I made sure to scrape the paint down to get a good ground, on both spots when mounting the now switched coils.

This did seem to make a difference. Today, took it out to the lake with a friend of mine who has a timing light. It ran GREAT when we first got there, rode around for not quite an hour. Headed back to the ramp, having to come to idle while passing under a bridge. Before going back up to speed, we sat there discussing what all I'd done to the motor while it was sitting there idling, maybe 6 or 8 minutes total idling under the bridge and us shooting the breeze. Went to power up to get on back, and it wouldn't come up at all. he put his light on #1, and weak to no signal on that plug. We didn't have the time when we got back to the ramp to swap the power packs around, and he needed his timing light so I couldn't borrow it for using in the morning to switch the packs around and test the firing again.

My question is this, a power pack is either good or bad? or is it possible for it to be ok, then 'bug out' and drop a cylinder? Before you put in the link for the CDI page, I've been there looking at it already, I don't have the right meters to check the DVA, on the packs or the stator. Is it time for me to bite the bullet and go put this in the shop, or should I try just picking up a power pack and switching it out first? that would be the cost of the pack obviously, but it would save me the cost of the labor at the shop. I guess I could go rent or buy a timing light and change them out and test it. The thing is, when we put the light on it when we got to the lake, it was fine. So again, is a power pack one of those 'either it's good or its bad' kinda things, or is it possible to be fine for a while, then bad for a while, then fine again, etc etc.....

As always, thanks in advance for any help and advice! Chaz

 

[Bosunsmate]

Re: About power packs......

Sometimes the bolts can be rusted and need replacing to get a good ground, otherwise id say powerpack, cheaper than the timing base....

 

[papachaz]

Re: About power packs......

the bolts on the coils or the power pack? I've made sure the #1 coil is grounded. I can pick up a power pack for under $100 online, haven't called the local shop yet. I am thinking I may just change out that power pack and then if that doesn't get it, just take it in and let them run some DVA tests and diagnostics on it. Thing screams when it's firing right though. No goop coming out from under the flywheel, no indications of the stator from that aspect anyway.

thanks Bosunsmate, I'm thinking I'll just change that pack and see if that gets it

 

[Bosunsmate]

Re: About power packs......

I was thinking the ground on the coil but if you have swapped that coil, you know its grounded ok and kept it swapped (ie not put back the original one on there) and its still playing up on that cylinder then it does indicate powerpack or timing base.
I find if its intermittent it is more often than not the powerpack giving up the ghost.
If its got good spark on all other cylinders when number one is dropping out it rules out the stator in my caveman rulebook
You could just change the powerpack over and check spark again. Check spark on all cylinders.
Ive being in this situation often myself but on single powerpack engines, ive won and lost but i suppose its not too much of a loss to have a spare powerpack around if it isnt it

I had one lately with no spark and it was because someone had covered all the headbolts threads in gasket goo so the whole head had hardly any ground to the crankcase

 

[emdsapmgr]

Re: About power packs......

Weak ignition components tend to fail once the engine heats up to normal operating temps. That engine will run coolest when planing-the pressure relief valves open and flood the heads with extra cooling water. Once the engine returns to idle, all cooling goes thru the two stats only-the engine heats back up to around 150/155. This "normal" idle heat could be enough to trigger an ignition component failure on any "weak" component. That engine has two power packs on it, one for each head. You can test your spark problem by swapping the two power packs. Run the engine till it is fully warmed up. Then idle it for 10 minutes-in gear. If the "no spark" conditon moves from #1 to #3 after the swap/test, you've got a bad pack.

 

[papachaz]

Re: About power packs......

thanks guys! both right on the money with what I was thinking. Like I said, wish we'd have had enough time to change the packs out and check again. the other cylinders were firing, he did check that while he had the light hooked up. Time to see what I can find a power pack for, or more like who local has one and just try changing it. and as bosun said, it can't hurt to have an extra handy if it turns out NOT to be that. tough to be on a fixed income and not have the money to go ahead and just fix it when I want.

the only thing that concerns me with your answer emd is that it's done it both ways the last few times out. yesterday, it ran great when cold, time before that it seemed to do better once it warmed up. Of course even at that, it ran like a screaming eagle for a short time, then back to bogging out and, I assumed, dropping that cylinder

 

[emdsapmgr]

Re: About power packs......

Sounds like you're getting a new pack. Hopefully that will take care of the issue. Let us know how it works out.

 

[boobie]

Re: About power packs......

Without any testing with a DVA, I'd have to guess a bad power pack as heat can cause them to act up.

 

[papachaz]

Re: About power packs......

yeah boobie, I know it needs a DVA test done, but I don't have the right tools for the job. I called my local parts dealer to price/order a power pack. The "man" was out on a service call and was supposed to call me back, but never did. Son in law called me and somehow managed to have the day off today. I went and picked him up, we went to the river. Boat ran ok cold, about 4 miles up the river we pull into one of our favorite backwater fishing holes. Coming off WOT to cruise in, it started missfiring again. I shut it down, as we needed the trolling motor for fishing anyway.

fishing that backwater thoroughly for a few hours, motor started up, came out of that honey hole to move to another, motor ran fine. fished a few more hours, headed back in. Ran like a scalded dog back down the river to the ramp, but when I came out of WOT again, it started the misfire. So basically, y'all are right in that it acts up worse when it's at full operating temp. I will get one ordered either tomorrow or monday, change it out and head back out one day next week for the test run. Will definitely post the details of the trip for future posterity!