1974 Lark 50hp 50472M - Suddenly no spark?

[lent0n]

Everyone loves a mid-summer boat repair right?

I got the boat out a couple weeks ago and I've been having a blast, up until this Tuesday evening.

I went to take it out and got an engine cough (near start) and then nothing. Starter spun like a top and not a single bit of life from it. I figured I flooded it and called it a day, took the battery off and brought it home to check the charge, just in case I was mistaken on it's speed (needs 250rpm to send spark). Battery is all good.

Presently I'm getting zero spark on the plugs, I've checked the ignition coils and they seem to be within spec, they're also getting no power from the power pack.

Now I've gone and gotten my hands on the original owners manual and the recommended testing equipment is highly outdated, neon lights with switches and multiple leads and spark testers that are a flat panel with multiple leads. I've also attached the relevant section to this post as well as the CDI testing guide, which of course requires a DVA which I don't have.

CDI Testing Results (Without DVA)
Brown - GND - 650Ohm
Black/White - White/Black - 15Ohm
Black/White - GND - low reading not OL
White/Black - GND - low reading not OL

My test light is not showing any power coming in or out of the power pack presently, but I don't recall if I checked the charge coil (Brown) line yet.

The rectifier was absosutely falling apart, but the engine didn't start without it

As far as successful testing I can say that it seems as though there's simply no electricity coming from anywhere except through the starter solenoid/starter.

My ask here is does anyone have a guide or sense of how to use a fluke meter to check the powerpack, charge coils, stator? Volts/Ohms, any guidance appreciated.

Also is there something stupid that I'm missing? Like it feels like a ground is missing or a line fell out, just something stupid that I can't notice. It just seems extremely weird that it almost started and now I'm getting zero spark and no power anywhere.

Apologies that this is a bit of a long-winded post I've been in the sun trying to test this stuff since it's at the dock and I don't have a means of towing it to the launch presently.

Currently have ordered a replacement rectifier and powerpack since amazon can have them here Friday and I can return the power pack if it's not necessary.

Please feel free to ask questions, happy to clarify, I'm just trying to get back out there!

 

[LaqueRatt]

Defective kill switch/button maybe grounding out your electrical system? Just a guess.

 

[lent0n]

Defective kill switch/button maybe grounding out your electrical system? Just a guess.

Killswitch being at the key switch? I never really thought about that as a possibility.

In the instructions it has an option to disconnect the keyswitch and test it without. So I'll give that a shot. The key switch is beat to **** so that wouldn't necessarily be a surprise, but also much happier to fix that vs trying to find a replacement stator

 

[racerone]

Stator for a 1974 model 50 HP is not hard to find at all.

 

[lent0n]

Stator for a 1974 model 50 HP is not hard to find at all.

I guess a different way of putting it is, it's not on Amazon. Which gets here fast and I can return easy.

 

[lent0n]

Defective kill switch/button maybe grounding out your electrical system? Just a guess.

So I tried starting the system with the black/yellow - keyswitch cable disconnected from the powerpack and it still no spark. I'm thinking it must be the stator which is a huge headache. Cheapest one seems to be $300 Canadian and I'll definitely need it out of the water to switch it.

Gonna wait til the DVA arrives to complete testing and verify before I go ahead, but cant seem to find anything that points to anything else unfortunately.

 

[racerone]

In Canada----evinrudeparts.ca-----may offer help.

 

[lent0n]

In Canada----evinrudeparts.ca-----may offer help.

That's where I'll likely be getting the replacement!

 

[racerone]

What ohm reading do you get on the stator brown to brown ?----And one brown to ground?

 

[lent0n]

What ohm reading do you get on the stator brown to brown ?----And one brown to ground?

My fluke gave back 880 I think, or .880 I'll have to double check, pros and cons of fluke meters is the moving decimal. There's nothing on the CDI regarding anything ohms resistance, just what to do about DVA.

I don't believe there's a way to get brown to brown without removal of the flywheel, correct? Unless there's another brown I'm not aware of but as far as the owners manual is concerned, the brown leads directly to the stator which I can't access presently, I can access the yellow stator wires

 

[racerone]

edited.

 

[lent0n]

???----No need to remove flywheel to check brown to brown.

Where would the other brown end be?

I've got one end coming into the charge coil slot on the power pack and that leads directly into the flywheel area.

I've attached the owners manual diagrams for testing and you can see it go into the charge coil. Happy to know if there's another spot

 

[racerone]

My mistake ---I guess there is only 1 brown.-----Have not worked on a 74 model in a long time.

 

[lent0n]

My mistake ---I guess there is only 1 brown.-----Have not worked on a 74 model in a long time.

No worries! I was hoping to be wrong in this case. Since you're likely more experienced than me. Should I get my boat towed out of the water for a stator replacement or can I manage a flywheel removal and reinstallation at the dock?

I'm assuming to complete this job I'll use my impact drill to loosen the flywheel nut, and then use a flywheel pulling kit to get it out, replace the stator and run the fresh wires out and then reassemble. Is there any timing elements I need to be worried about or will that remain stable because the timing elements are remaining unchanged?

 

[lent0n]

Update for anyone following or reading.

Got the DVA adapter today and the power pack is the culprit, thankfully the stator was cranking out plenty of power.

Now I'm just going to incredibly and meticulously verify that my keyswitch wiring is solid, read enough forum posts about power packs blowing from switches twisting, going to to add some rubber covers for all the ends as well to make sure they stay nice and clear of each other.

 

[lent0n]

My mistake ---I guess there is only 1 brown.-----Have not worked on a 74 model in a long time.

Couple questions for you. I've noticed a couple things in my evenings spent testing the motor.

One is some black grease type substance leaking from under the flywheel is this cause for immediate concern? I don't seem to find a ton of information online.

I've also noticed the ignition coils have some surface cracks but they don't look 'cracked open' there doesn't seem to be a ton of photos of online of what to look for but am I to assume that any cracking is worth replacing? These seem to be originals.

I've also noticed that the spark plugs I've been using (just been replacing the ones that came with it with the same type) are also a different model. Could this be the source of some of these problems?