1978 Evinrude 115 running rough

[Glassmaster77]

Purchased the boat 2 months ago. Been out 3 times. First time out motor was very hard to start after sitting up for several months. Ran OK, just had low idle. Would stall when going into gear. Pushed a 16' fiberglass Glassmaster 40 MPH with 4 adults. Plenty of power. <br /><br />Second time out, the starboard coil came unplugged after putting the engine cover back on and we limped back to the dock and trailered it home and discovered the problem. On the muffs it ran fine after plugging back up. Bumped up the idle and you can start it with a rope when its warm.<br /><br />Third time out, took it out about 10 miles up river and anchored for a few hours. On the return back at WOT running smooth it stumbled & then died. Started back up and ran rough. Limped back to dock. Trailered home and checked it out. Everything plugged and well grounded.<br /><br />It will start right up and run with the warm up lever slightly up. Drop it to idle and it coughs and misses and runs very rough.<br /><br />Changed spark plugs. Ran it about 10 minutes on the muffs. Port side top plug is black and wet. Other 3 are clean. Port power pack passes diode test. Spark present when I pull the plug wire and there is an RPM drop when the wire is removed completely from the plug. <br /><br />Can a power pack be bad on one coil?<br /><br />Does this sound like a weak or bad coil?<br /><br />The port power pack is blue and a different part # than the Starboard one which is black and part # 582125<br /><br />Compression is 120# on all four cylinders.<br /><br />Motor is strong and comes up quick. Thanks in advance for any help.

 

[Walker]

Re: 1978 Evinrude 115 running rough

Sounds like dirty carbs to me.

 

[Glassmaster77]

Re: 1978 Evinrude 115 running rough

I'm leaning in that direction. No clue as to when they were overhauled last. I feel like the starboard top cylinder is firing, there just isn't enough fuel there to get 'er done. I'll order a gasket kit and new needles and see what that does. I'll post results.<br /><br />Thanks

 

[KYHunter2]

Re: 1978 Evinrude 115 running rough

Nothing to do with your problem .<br /><br /> But if you dont know when the waterpump was last rebuilt .<br /><br /> Good time to do it .<br /><br /> Good-Luck,<br /><br /> KYHunter

 

[Glassmaster77]

Re: 1978 Evinrude 115 running rough

Next item on my list. Ordered a fuel pump rebuild kit also. Thanks.

 

[emdsapmgr]

Re: 1978 Evinrude 115 running rough

Sounds like the port side top plug may not be firing. If you have a timing light, run the engine and test each lead for strong, constant spark. Try swapping coils and see if the problem moves. If not, you may need a new pack.

 

[Glassmaster77]

Re: 1978 Evinrude 115 running rough

That coil is the one that came unplugged and ran that way for about 40 minutes. We were in a river with a bass tournament going on and boats were zipping all around. We were afraid to stop for fear it would not start back up.<br /><br />I suspect that port pack anyway. I may just get two new coils & replace that pack just to be sure.<br /><br />There is fire there. It has spark when you pull the wire while running, either its not hot enough, or there isn't enough fuel in that cylinder. Hope to get to mess with it more during the week. Keep the ideas coming!<br /><br />Thanks

 

[KYHunter2]

Re: 1978 Evinrude 115 running rough

You can make a good spark tester , very easily.<br /><br /> That you can test all cylinders at the same time.<br /><br /> I like to test all cylinders spark, at the same time .<br /><br /> You can compare the spark, and see how each is firing . <br /><br /> Its alot easier to see a weak spark, when you have the rest to compare to.<br /><br /> Good- Luck,<br /><br /> KYHunter

 

[Glassmaster77]

Re: 1978 Evinrude 115 running rough

OK, I think I found the problem. I switched the wires and tried the top port coil on the bottom port cylinder. That plug got dirty and the top one cleaned up after about 5 minutes on the muffs. I figure the coil is failing. It fires fine for a few seconds then misses a few times and then repeats. I ordered a new coil and a power pack just in case. I cleaned out the jets with carb cleaner & compressed air and that made things smoother. Water pump over haul, carb overhaul & fuel pump overhaul to be done over the next few weeks. Thanks for all the advice given. After I get the parts installed I'll update. Be safe!