Just bought a 1977 85 HP Evinrude as part of a package deal.Before trying to run it I bought a new gas tank, new gas line and primer bulb. New gas and fresh mix.First try on the lake it started up OK, and seemed to run fine, although with a bit of vibration.After running for about 15 minutes, the power began to surge, the vibration stopped and we were going faster ( for only a few seconds at a time).Back at the dock, #3 cyliner seemed to be cooler to the touch than the others. Pulling the plug wire from #3 cylinder had zero effect on the motor.Swapped the plug from #1 to #3 and no change. The #1 cylinder worked great on the plug from #3.Pulling the #3 plug and running the motor I could not see any spark at the plug with it grounded out to the block.Please, give me some troubleshooting tips. Thanks,CarlCheney, WAPS: I hope I can get this motor fixed, because with only 3 jugs hitting, my 27 foot pontoon barge is kinda pokey!
Carl - Welcome to the place to get more info on boats & motors than any other. - - - Some of the asvice is actually pretty good.Just as you swapped the #3 plug do the same with a plug wire on #3. If no change repeat the process with a coil.
After reading about a zillion posts, it seems that the coil & plug wire, the powerpack, and the #3 sensor are the three most likely culprits.The boat and motor are a long way away and not near any repair shops or parts supply.I've taken off the coil and brought it back to town.Using my multimeter, I measured the resistance of the coil.Between the wire that goes to the power pack and the ground wire I measure about 0.15 ohms.Between the plug wire connector and either of the other wires is open (infinite resistance).From any of the three wires to the metal core mounting is also open.Is this correct? I was expecting to find some indication from the plug wire connector to one of the other wires.