Cold wet Spark Plug after running engine; coil good; powerpack? Evinrude 140 v4 vro

[irocz_man]

After motor started running rough/stalling at low speed, tried WOT and didn't get usual take-off/speed/RPMs (fuel, compression are good) and I thought spark was too; stopped to pull plugs and have a look at them - 3 were warm under plug boot, 1 cold, 3 warm ones all looked normal/good, but cold one was kind of wet and black - wet fouled I would call it. Swapped plugs, same result on that cylinder. Switched 2 coils, same plug/cylinder was cold after another run. That eliminates coil right? That plug has spark when you pull and hold to block while cranking engine, but I think is losing it under power - Sound right? Powerpack probably?

Any insight or advice you could give will be much appreciated! :joyous:

 

[Daviet]

Re: Cold wet Spark Plug after running engine; coil good; powerpack? Evinrude 140 v4 v

Use a inductive timing light when the cylinder fails to see if you are loosing spark at high speed. If you have good spark, you might check and see if you might have water intrusion and causing the cylinder to misfire.

 

[Bob_VT]

Re: Cold wet Spark Plug after running engine; coil good; powerpack? Evinrude 140 v4 v

Do you have dual power packs? My V-4 does. Swap them and see if the problem moves with the swap. I was getting an intermittent spark and just installed a new power pack. The swap should take you about 10 minutes

 

[irocz_man]

Re: Cold wet Spark Plug after running engine; coil good; powerpack? Evinrude 140 v4 v

Daviet are you saying to put the timing light on it while in the throttle on the water?
How would I check for water intrusion? And can that happen in just one cylinder?

 

[irocz_man]

Re: Cold wet Spark Plug after running engine; coil good; powerpack? Evinrude 140 v4 v

Thanks Bob_VT - Mine has the single power pack though, wish I could just swap 'em like you did to test.