1979 merc 80 missing on 2-3

[bgrinde]

I have a 1979 merc 80 outboard, we just got the boat a month ago and have been working on getting to run right, It currently is only running on 2 cylinders number 1 and 4, 2 and 3 are not getting any spark, on the lake after 15-30 minutes it will start hitting on all 4 cylinders, by the time you load it and bring it home it is back to running on 2 cylinders again.
Is it the trigger or stator, or switch box?
the ser# is 5141221
Thanks

 

[sschefer]

Re: 1979 merc 80 missing on 2-3

I would bet that if you did a compression test you'd have your answer.

 

[bgrinde]

Re: 1979 merc 80 missing on 2-3

I have good compression, No spark on 2-3 at the plugs or at the coils.
Any help would be great,
I am trying to narrow it down to the stator, the switch box or the trigger assembly.

 

[sschefer]

Re: 1979 merc 80 missing on 2-3

Do you have the steps and spec's for the electrical tests?

 

[bgrinde]

Re: 1979 merc 80 missing on 2-3

I dont have the steps, I have done some ohms test with no results

 

[ozarkglen]

Re: 1979 merc 80 missing on 2-3

I may be wrong, but I have '78 800 and have had simular problems. I believe the trigger fires 1 and 2 off one wire and 3 and 4 off the other. These wires are connected to the switch box. Since your problem is cylinders 2 and 3, I think your trigger coil is probably good. To test, switch the coil wires on the switch box from cylinders 1 and 2. Of course do not try to run the engine, just test for spark. If the spark moves (2 fires but 1 don't) the problem is the switch box. Do the same test for 3 and 4. If the spark does not move the problem is probably the coils. Be sure to correctly install all wires before trying to start engine. Hope this helps.