Evinrude 50 2 stroker problems....

[Longknife 76]

Got the boat out last month and it would not run right. It started and ran good for about 5 minutes and then started to miss-fire on the lower cyl??? Don't have any test equip so I did a shade tree diagnosis, Replaced the plugs, drained and put in new fuel, cleaned fuel filer, replaced coil and wires, and replaced the power pac.... Each time I would replace an item I would take it to the marina and put it in the water to test run it, Each time it will run good for about 5 minutes and the #2 will start missing. I pull#2 wire and it keeps running (poorly), put it back on and pull #1 and it dies...,What is causing this , I'm out of "Guesses"?....Thanks, ED
 
(its an E50TSLECC)

[fatercat]

buy some sea foam and get the carbon out. run like hell

[KNIFE_NUT_1981]

Sounds to me like it's runnung just long enough to heat up the ignition coils. When the one on the bottom heats up, it opens up and stops firing. But that's just a guess... You need more equipment in order to make a definite diagnosis. Beg, steal, or borrow yourself a spark-gap tester, install it between the bottom spark plug and boot, and fire her up. Assuming you have new plugs, watch your spark-gap tester until it begins to run bad (the gap needs to be set so that the engine still runs well, but you can see the spark across the gap). If you lose fire when it is running bad, then I would replace the ignition coil for the lower cylinder, but these are not exactly cheap, so make sure you perform this test first to make sure. Hope I helped a little...