Need help with intermittent miss.

[HookedOnReds]

I have a new to me 1980 115hp Evinrude, my 1st outboard. 90psi comp. on all 4, new plugs and wires,carbs rebuilt. Starts easy cold and idles on its own after 15secs. My issue is an intermittent miss that can be seen on all cylinders with a timing light, appears to happen at any rpm and either cold or hot. Charging system was at 12.5v and noticed cracks and a burnt area on stator. Installed what appears to be a good used stator(no cracks or burns) and is now charging 13.8v but still has missfire. Seeing that miss is across all cylinders would the timer base be the next area to look at?

 

[Faztbullet]

Re: Need help with intermittent miss.

I would look at rectifier 1st as bad one can cause this. Just disconnect stator leads and see it problem goes away. If it does not check for voltage on blk/yel wire to pack and disconnect the to verify no wireharness of key switch problem..

 

[HookedOnReds]

Re: Need help with intermittent miss.

I did a diode check on rectifier and appeared ok. Tomorrow I will disconnect it and see for sure. Thanks

 

[emdsapmgr]

Re: Need help with intermittent miss.

13.8 volts is a more "normal" reading and would indicate that it is now recharging the battery. Random intermittent spark can be a weak stator, but yours was just replaced and it's unlikely that both are bad. Is the spark intermittent on all plugs, or just one in particular? If the spark is intermittent on one plug or both plugs on one side, you can swap the power packs and see if the problem moves. Same with the spark plug coils. CDI electronics has a nice troublshooting section if you don't have a factory service manual: CDIelectronics.com. Check out pages around 34-35.

 

[HookedOnReds]

Re: Need help with intermittent miss.

It is a random intermittent miss on all cylinders seen with a timing light attached to each.

 

[HookedOnReds]

Re: Need help with intermittent miss.

Disconnected rectifier today after an awesome dinner and no change in misfire.
Had an after thought and could it be possible that spark plugs could be fouling slightly because the only run time it has seen has been on the muffs since I aquired it and got it running? Maybe I should get it out on the water and open it up to clean it out.

 

[emdsapmgr]

Re: Need help with intermittent miss.

Check your stator output. If it is weak/low output, you can get random misfires.