1990something 120hp Evinrude. Last two times it's had problems after running a while. First time I ran it hard about 40 minutes out and then the RPMs started dropping a lot (from 4500 down to 2800 or so) with some very minor vibrations and then coming back, or else staying down until I ran it slow for a while then if I hit the throttle it would rev right up for a while and then repeat. Ended up going back in running perfectly at 1500-2000rpms.
Hoped for a simple fuel issue and cleaned out the carbs. Then I took it out again and this run avereged 3000rpms and then we did slow trolling for about 2 hours with no problems whatsoever and was convinced from running it for hours that it was fixed... 15 minutes into the 30 minute trip home, at my normal ideal range of 3000-3500 the problem started up again and I took it in slow with no issues whatsoever.
So now I am thinking the coils are overheating. Then once I got to inspecting the coils I noticed some well camoflaged by grime electrical tape on one of the wires covering this notch.
Question now is can I test both of these with a multimeter to find out if one is the issue? I'll definitely be replacing the wire asap but would like to be able to test it for obvious issues and am not sold on it having been the problem because the motor's been running hard since I bought it in 6 months ago. I have a spare brand new coil to compare coil results with if I can test this way. Would like very much to be able to troubleshoot this on land hopefully not have to wait for it to resurface several miles out and do my troubleshooting through parts replacement electrical work leaning over the side.
In the pic that's the coil I suspect, the brownish part seems ominous though I have no experience with this so input would be great. All of the coils have some light hairline cracking around the edges of the goo.
Hoped for a simple fuel issue and cleaned out the carbs. Then I took it out again and this run avereged 3000rpms and then we did slow trolling for about 2 hours with no problems whatsoever and was convinced from running it for hours that it was fixed... 15 minutes into the 30 minute trip home, at my normal ideal range of 3000-3500 the problem started up again and I took it in slow with no issues whatsoever.
So now I am thinking the coils are overheating. Then once I got to inspecting the coils I noticed some well camoflaged by grime electrical tape on one of the wires covering this notch.
Question now is can I test both of these with a multimeter to find out if one is the issue? I'll definitely be replacing the wire asap but would like to be able to test it for obvious issues and am not sold on it having been the problem because the motor's been running hard since I bought it in 6 months ago. I have a spare brand new coil to compare coil results with if I can test this way. Would like very much to be able to troubleshoot this on land hopefully not have to wait for it to resurface several miles out and do my troubleshooting through parts replacement electrical work leaning over the side.
In the pic that's the coil I suspect, the brownish part seems ominous though I have no experience with this so input would be great. All of the coils have some light hairline cracking around the edges of the goo.
