I've got an 86 Evinrude 70 3 cyl thats started having idle problems a while back. It liked to die when you first put it into gear but ran great at anything above idle.
Yesterday I found some air leaks around the primer hoses on the carbs and fixed that. Took it out this morning while it was still cool and it started and idled fantastically well and sounded like a new engine while we ran at low speed to get out of the harbor speed zone. Cruise and top end performance were mostly unchanged although it sounded better/smoother at cruise speeds - 4k rpm or so - than it had before.
However, after a 3 mile cruise we stopped and the idle was bad again. Not quite as bad as before but not great. It wanted to die when put in gear and was more difficult to start requiring lifting the idle-up lever more and pushing in the primer more. Over the course of the next hour it seemed to get worse and worse until I had to turn up the idle speed a lot just to keep it running at all.
It ran rough and sounded like it was only hitting on 2 cylinders.
Once it was in gear and I was able to keep it going long enough to start building up speed, it would run rough until it had speed up to maybe 3000-3500 rpm then it was like throwing a switch and all of a sudden it was running on all 3 cylinders and it took off like a shot and ran great at any speed over about 3000-3500 rpm. When slowed down it started missing again.
Im having trouble deciding if this is an ignition or carb problem. The fact that it ran great when cold leads me to think it may be a bad coil or pack that acts up when hot, but why would it run great at speed?
I plan to test spark and compression in the am then see how it runs cold again. Im hoping to at least narrow it down to see if its a heat related problem for sure or not.
Any other suggestions or ideas would be great.
Thanks!
Larry
Yesterday I found some air leaks around the primer hoses on the carbs and fixed that. Took it out this morning while it was still cool and it started and idled fantastically well and sounded like a new engine while we ran at low speed to get out of the harbor speed zone. Cruise and top end performance were mostly unchanged although it sounded better/smoother at cruise speeds - 4k rpm or so - than it had before.
However, after a 3 mile cruise we stopped and the idle was bad again. Not quite as bad as before but not great. It wanted to die when put in gear and was more difficult to start requiring lifting the idle-up lever more and pushing in the primer more. Over the course of the next hour it seemed to get worse and worse until I had to turn up the idle speed a lot just to keep it running at all.
It ran rough and sounded like it was only hitting on 2 cylinders.
Once it was in gear and I was able to keep it going long enough to start building up speed, it would run rough until it had speed up to maybe 3000-3500 rpm then it was like throwing a switch and all of a sudden it was running on all 3 cylinders and it took off like a shot and ran great at any speed over about 3000-3500 rpm. When slowed down it started missing again.
Im having trouble deciding if this is an ignition or carb problem. The fact that it ran great when cold leads me to think it may be a bad coil or pack that acts up when hot, but why would it run great at speed?
I plan to test spark and compression in the am then see how it runs cold again. Im hoping to at least narrow it down to see if its a heat related problem for sure or not.
Any other suggestions or ideas would be great.
Thanks!
Larry
