Mariner 25 Ignition Problem

[Rock Hall]

This is my first post to this board. Thought I could handle the problem myself, but I need help. Here's the story:<br /><br />I have a 25HP 1986? MARINER. This motor has been flawless up until a few weeks ago. I was running at about 2400 RPM (guess)and all of the sudden it was like I hit something motor just shut off. I didnt hit anything I,m sure. The motor would not restart. Tried to start, was like the kill switch was on. Then tried it again 45 min later as the tow boat was heading out and it started. Ran for about 30 sec and shut off again. I kept trying to start it over the next few days and nothing. I took it home to dig in and try to figure out what was wrong. <br /><br />Using a spark tester, I determined that there was no spark at either cylinder. After running this by a few mechanics, I was told that it was most likely the switch box. The only way to test was to bring the boat in and have them test it with everything assembled. 2 week wait. I opted out of that idea.<br /><br />After getting gouged on a new switchbox, I installed it and nothing changed. My next thing to try was the stator. My ohm-meter showed a dead short on the low speed coil. So I ordered a new stator installed it and WALAH, first pull it started. It didnt seem to be running 100%, but I thought I'd wait till I got it in the water and see how it runs. Put it in the water over the weekend. Started first pull, seemed to run ok, except it was breaking up pretty bad it high speed. I fooled around with the timing linkage and it seemed to get better. Ran about 90% good. Ran it around for about an hour. Next day, put it in the water and it seemed to run ok, not great but ok. Pulled it out of the water, put it on the trailer and took it 5 miles down the road to another ramp. Loaded it up with a few guests, pulled the starter and nothing. would not start after an hour of pulling totally dead. an occasional fire, but no start. after putting new plugs in and rigging the starter so that I could give it 3/4 throttle to start, I got it to run on one cylinder.Pulled it out took it apart and determined that there was no low voltage coming from one side of the switch box tested coils wires and plugs by switching them to the other cylinder. So I figured the switchbox fried on one side. No problem since I had another swichbox at home. Brought it home and tonight installed the other switch box. started first pull, but only one cylinder, but ran better on one cylinder. Tested for spark and sure enough, the top cylinder is dead. I did see some spark on one pull, that was it. so I think I'm getting an occasional spark on the top cylinder, but 90% of the time nothing. checked all the grounds and the connections. The only ignition part I didnt replace was the trigger coil. I'm not sure exactly how that works so I dont know if it could cause this problem. <br /><br />Thanks in advance, I hope someone has some suggestions.<br /><br />Mark

 

[Laddies]

Re: Mariner 25 Ignition Problem

Mark, first ck the magnets under the flywheel they will come lose, next the plugins at the switch box there are a couple that are easy to get mixup and that will cause it to run on 1 cyl. if they are alright then you need to OHM test the stator windings there is a high and a low winding. the trigger is a single winding that feeds off both ends so if it don't work on 1 it won't fire the other cyl

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

Originally posted by Laddies:<br /> Mark, first ck the magnets under the flywheel they will come lose, next the plugins at the switch box there are a couple that are easy to get mixup and that will cause it to run on 1 cyl. if they are alright then you need to OHM test the stator windings there is a high and a low winding. the trigger is a single winding that feeds off both ends so if it don't work on 1 it won't fire the other cyl

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

Thanks for the info.<br />I checked the magnets and they seem ok. All the wires match in color on the switchbox. The stator is new, but I ran out of daylight before I got to test it. I will check it tomorrow afternoon. I'm really baffled on this one. new switch box and new stator. All non-returnable. I have 2 switchboxes, both of which should be good.<br /><br />Also, if the stator goes, wont it effect both cylinders? The motor actually starts first pul and runs on 1 cylinder.<br /><br />Mark

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

ok<br /><br />Took everything apart again. everything looks good. put it back together and I still have intermintent spark on same cylinder. I usually have no spark, but about 10% of the time I see spark on that cylinder. There is no current coming from that side of the switch box. switched the coils around to make sure it wasnt a coil or a wire. checked all connections. An outboard guy told me he has seen a bad trigger cause this problem. Could he be right? It's the only thing I havent replaced. Also, through all this, the timing link has been changed a few times. When I rev it up, it seems to smooth out a little, hard to tell with no load and I dont like revving it on the garden hose.<br /><br />Any comments?<br /><br />Mark

 

[Laddies]

Re: Mariner 25 Ignition Problem

Mark have you interchanged the coil leads to ck the coils

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

yes.<br />both coils are good

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

I ordered a trigger today. the only thing left to replace.

 

[Rock Hall]

Re: Mariner 25 Ignition Problem

Laddies,<br /><br />Looks like the problem is the flywheel magnets. Thanks much for your help, I learned alot.<br /><br />Mark

 

[cuda-cable]

Re: Mariner 25 Ignition Problem

i'm having a similiarproblem..........how do you check the magnets for tightness? and how are they secured in place??....thx