Outboard troubleshooting...I think no spark?

YeOldeStonecat

New member
Hello all....
2x summers ago I picked up a used Merc Offshore 125 for my Baja SS18.
4 cyl, from a user outboard rebuilder...so naturally no owners manual. It ran great over the past 2 summers....always started up quickly, idled fine, overall a nice reliable engine.

I live in New England...CT. Boat is trailered. Pull battery for winter storage, trickle charge towards early spring and then again before putting battery in boat and connecting the ear muffs 'n hose and firing up the engine to blow out the winter fogging oil in the cylinders.

2x weekends I put in a new fuel line switch to alternate between the front tank and rear tank. I flipped it to the rear tank and fired up the engine for the first time this year. Started fairly well for the first firing of the season. Ran for almost a minute..then started struggling. I figured.."Ahh..stale gas from the rear tank which I didn't fill last year". So this weekend after more cleaning of the boat, flipped the fuel switch to the front tank, drained gas from the engine to get out the stale gas, and went to fire it up again. Turned over fine...but never even began to catch. Check plugs...wet. Dry plugs, try again...no luck. Repeated several times.

So take a plug out and hold it against a ground on the engine..have someone turn it over. Not one spark. Tried another plug..no spark..same on 3rd plug. Eyeballed all grounds 'n wiring as best a novice could on the engine.

Where to proceed next? I know the battery isn't up to full snuff...volt meter on boat guages showing 9-10v maybe..but the engine is cranking over at a good speed, should be decent enough for a spark, no?

Mid to late 90's Mercury 125 Offshore model.
 

Bt Doctur

Super Moderator
Staff member
spark for the ign. is provided by the stator under the flywheel,the battery is only for starting and electric choke operation
the stator coils power the ign. system. and also has charging coils (AC) and a rectifier for DC charging.
 

YeOldeStonecat

New member
Alrighty....so the stator is sort of the equivalent of the alternator of a car?

The spark plug wires go from the plugs..to what looks like 4x individual little coil packs....or something like that. From that coil pack...I take it it's fed by something coming down from the stator?
 

Bt Doctur

Super Moderator
Staff member
the stator feeds an amplifier that the coils are hooked up to. The ign. trigger is under the flywheel .this tells the pack when to send the spark to the coil.
Can you supply model and serial number
 

YeOldeStonecat

New member
Should be able to find something tomorrow...
Serial number and exact model of the outboard?
Serial numbers give any hint of year of the model?

I'm fairly mechanically inclined....taking off the flywheel any big deal?
 

Bt Doctur

Super Moderator
Staff member
loosen /remove the large nut, install puller ,remove flywheel.
BUT there are some tests before you do that.most likely your triggers are magnetic, no real adjustments
On the transom mount is a metal tag with model and serial numbers.
you measure the voltage supplied by the stator at the amplifier terminals first.
You could also try unplugging the main harness plug on the motor and jumping the starter solenoid .Outboards shut off by supplying a ground to the ign system,removing this ground allows them to run. To shut it off pull the fuel line or the plug wires.If it runs without the harness plug, the trouble lies in the harness or the key switch assembly.
 

YeOldeStonecat

New member
Thank you for the replies...
Raining most of this week, hopefully some evening this week it will not be raining and I'll get a chance to get outside and tinker on it. Those April showers are running late this year! :doh:
 

YeOldeStonecat

New member
Update...

I need to be slapped in the face with a trout.

The emergency kill lanyard..she was pulled a bit, the toggle switch on the controls under the key was pulled down. My eyes didn't see when attempting to start before, since I was standing on the ground and reaching over to turn the key when attempting to start it earlier.

Oh boy...my wifes blond moments are rubbing off on me. :poke:
 

Bt Doctur

Super Moderator
Staff member
That only means you contracted a case of the dreaded
C.R.S.
Not fatal ,no cure but sure does mess with the brain cells.
"Can`t Remember Sh*t
Now get out there and catch that Trout
 

YeOldeStonecat

New member
:drink:

Heh...yeah...life after 40! She fired right up last night on the first turn.

Now...to hope the sun comes out this weekend and get her wet! (the boat...not the wife...)
 

Bt Doctur

Super Moderator
Staff member
Well, that depends on the worm. If your going to fish for the ultimate catch or just get the worm wet.:thumb:
 
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