1977 115hp Evinrude

[freddyray21]

friend of mine got this on a Craigslist deal with a boat and trailer. He took it out last weekend and it ran fine out to the no wake and about 3 miles up the lake. They turned around to come back and on the way back he did a hard turn and the motor bogged down and would not pick back up. He idled it down and killed it then restarted it, but never would pick back up then it died and would not restart. We were actually out on the lake so towed them in. He brought it to me last night and of course it started and seemed to run fine. I did a compression check and found right at 120 on all four. When running it took a wire off each plug and found the starboard lower cylinder not firing. It's got very weak spark almost none at all so I suspect a bad coil there. Just thought I would put this out to see if anyone has had a similar problem.

 

[tashasdaddy]

Re: 1977 115hp Evinrude

swap the coil with another one, to verify. could have ran hot and shut down. the older motors have this problem.
Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs. besure to blow out pick up tubes also.

 

[ezeke]

Re: 1977 115hp Evinrude

If the ignition coils are discolored, cracked, swollen or if the potting material is deformed, they should be replaced. Most often, the ignition coils are on this series of motors are poorly grounded. Take the coils off and thoroughly clean the base and the grounding strap and then remount.

The rack on which the ignition coils are mounted was another source of poor grounding due to rubber grommets on the mounting bolts, so the grounding straps leading to the cylinder heads also need to be in top shape and clean.

Pulling sparkplug wires on running CD ignition systems can damage the power pack. Use a spark tester or inductive timing light instead.

 

[freddyray21]

Re: 1977 115hp Evinrude

good to know that zeke as I did not know. We swapped out the coils and the no fire did not change so I suspect the power pack now. The one coil that was not firing had a big crack in it on the underside. I wonder if that shorting to ground might have burnt out the pack concerning that cylinder. I need to check my manual to see how it triggers under the flywheel to see it that might be the problem. This is a whole lot newer motor than I am used to working on with a completely different ign.