Merc 115 Ignition Problem

Hello all: I have a 1979 Merc 115; dual switch blx, 6 coils. I have no spark on 1,3,5; I replaced the Switch Box but still no spark. Can you give me some troubleshooting tips?

Re: Merc 115 Ignition Problem

you could try swapping around the trigger wires -if the spark moves to the previously dead cylinders - trugger is bad - rare but they do go everyy now and then -highly recomend youget a dva meter or a dva adapter for your multimeter , get the book for specs -and after a few minutes of reading you'll be finding the problem in 20 minutes - dav adapters are sold here at iboats , cdi electronics,and ebay - a multimeter without the adapter wont work ( the readings will bounce all over the place -the adapter freezes them and gets the average

Re: Merc 115 Ignition Problem

Sounds good; I have a FLuke Digital Volt Meter, Same thing? I did find the problem; crosssed the trigger wires with the green coil wires; was a bad sitch box to begin with then i lost valueable time wiring it wrong - ha.

Re: Merc 115 Ignition Problem

the fluke meter will work - but does it have a "DVA" setting ? if not buy the dva adapter from any of the places i listed -it plugs into the meter where the test leads normally go and you plug the leads into teh adapter - the only way to test an outboard ignition .

Re: Merc 115 Ignition Problem

I'd test the stator.....

Re: Merc 115 Ignition Problem

Thanks and I will get the adaptor. I appreciate it.

Re: Merc 115 Ignition Problem

Wallyiii said:

Thanks and I will get the adaptor. I appreciate it.

Click to expand...

You need a DVA to diagnose performance problems. You don't need one to diagnose spark issues. A simple multi-meter is all you need at this point and you don't really even need that.

It's not the trigger, the trigger has three coils and the trigger magnet is north south on top and south north on the bottom. Picture it like this..
1 2 3 = trigger coils
----------------------
1 2 3 = spark plugs
4 5 6 = spark plugs

1 and 4, 2 and 5, 3 and 6 share a coil. Now you know why it isn't a trigger problem.

It could be the stator so swap the red and blue wires with the red/white and blue/white wires at the the switch boxes and if you now have fire on 1, 3 and 5 then the problem is the stator.

Re: Merc 115 Ignition Problem

Sounds like a Stator to me too. The Stator has 2 sides, each giving juice to 3 plugs. It also has a low and high side. Sounds like one of the low sides is dead. If you have it in the water and get the RPMS up around 2200 - 2500 the high side would kick in and I'll bet you would have spark in all 6. The trigger has 3 pickups and when one goes, you loose spark in 2 plugs. A single plug out is usually a coil. Switching the wires on the switch box is a great test to see if the problem moves to the other 3 plugs. Make sure the switch boxes are grounded when you run the test or they will blow.

Re: Merc 115 Ignition Problem

Thanks I checked the stator and after this was good I found I had crossed up trigger and the green coil wiring - now all is good. Thanks very much. Does anyone know if when the shifter is engaged in forward the prop is engaged in both directions - is this ok? Feel it should free spin counter clockwise but not sure - I did some work on LU. Thanks WT