1988 Mariner 150 total confusion

[matthewcaine35]

hello all, ive been searching for an answer to this ignition problem for a long time now and ive had enough where i had to join and ask this specific question myself. so i just bought a center cosole with a 1988 mariner magnum 150 and i took it out on the water shortly after some cleaning and minor repairs/checks. replaced the tilt pump, started on dog ears to check engine state and gears shifting properly. i took this boat out and it always cranked good but it did have a wierd super short spurt of high idle almost like a cough... anyway, went into gear fine ran fine but did get a little hot (my guess is due to previous people pulling out thermostats) so that trip was good and i figured i had a good motor. 2nd time around i took my wife and kiddo to the lake and the motor cranked but lasted about 10 secs before it died and did this repeatedly until i decided to put it in gear and see if giving it some gas would get whatever bug it had shaken out. well it started off good. i kept it at about half throttle just cruising and all of a sudden, DEAD. hasnt cranked back up to this day. first thing i did was check spark. didnt have spark so i researched and researched until i ended up buying a new stator. so as of right now i have a new stator that doesnt seem to be outputting hardly any ac voltage. i understand you need a dva to properly test output but i have a really good volt meter that records peaks and the highest it got was like 1.5V ac. i know for a fact i have the correct stator, ive triple checked but for some reason it appears im getting some rubbing on the inner flywheel/ outer stator. im pretty sure this is what is hindering my voltage. my question is, WHY in the heck would it be rubbing? and since ive been cranking on it for a while, should i expect this stator to be bad??? im going to try to add pictures of some of the things that i find suspicious. for example, when i pulled my flywheel the first time i found what appeared to be burn marks where it looked like the mating surface of the underside of the flywheel meets the top of the crank shaft. and it looked like the arc tried to travel towards the magnet. I’m out of ideas

 

[legalfee]

From the diagrams on marineengine dot com it looks like the stators have different lamination thickness. I would go to marineengine dot com and put in your serial number to be sure you have the right stator .

 

[matthewcaine35]

Already done, I have the right one but I just actually found something that may be the issue. After some close inspection, I’ve found a cracked weld on my flywheel which is a tale tell sign that it’s not spinning true resulting in the magnets slightly graising my stator.

 

[matthewcaine35]

So, this is my theory. at high rpm my old stator was working and sending power and then the flywheel scraped the stator thus grounding out and causing the burn marks on the mating surface. With the new stator in, I’m still making contact between magnets and stator metal and it’s not letting the stator do its job and not firing or firing sparaticly. Only more tests will tell. Will try some things when I get home. Like seeing if my crank shaft has bearing issues.

 

[Silvertip]

A flywheel should not have "welds". That thing is spinning at up to 5500 - 6000 rpm and is like a grenade if it comes apart at that speed. You apparently need a new flywheel.

 

[legalfee]

Yes you should not have a weld on the flywheel. I'd replace it.

 

[matthewcaine35]

this appears to be a factory weld. On the outter part of the flywheel

 

[matthewcaine35]

Some people mention bad bearings as well that could give the flywheel enough slack to touch the stator but I just put a dial indicator on the hub that the flywheel bolts to. Never left zero when I turned it several rotations. My flywheel still hits my stator even after quite a bit of air grinder sanding... anybody have a parts motor with a good flywheel?

 

[legalfee]

Here's one for 42.50

 

[matthewcaine35]

legalfee great find! Thank you!