I just installed an old 1980 85 horse on my boat that had been sitting outside laying on its side for probably 10 years. I had bought it a while back for $300 with the intention of a future project or to part out. My regular engine blew a couple weeks ago so I decided to put the 1980 85 HP on my boat.
So far I've done the following to the engine: removed probably 20 mud dauber nests from engine and carb, installed new starter (was missing), 2 new power packs (1 was bad), new coils (from my blown engine), new seals on lower unit, new impeller, rebuilt carbs (one was full of mud dauber nests), replaced all fuel lines with new ethanol resistant lines), new primer unit, verified great compression (125 psi on all 4 cylinders).
I ran her for the first time today. The engine ran perfect above 1500 RPMs. I took her to 5100 RPMs and it sounded tight, as good as a brand new engine. Perfect power through all RPM ranges. Temperature on the heads is 140 degrees after running it WOT.
Idling is another story though. If I run it hard it idles good for a minute or 2. The rest of the time it stumbles, it sounds good for 2 or 3 seconds and then dies abruptly. When starting it usually fires up fast and then may try to die 2 or 3 seconds later. Hitting the primer can help to keep it going.
I'm leaning toward a carburetor problem, especially since there had been a mud dauber nest in one when I rebuilt it. There were also fire ants in there eating the mud dauber larvae from the nests. All jets were removed and cleaned before but I'm thinking maybe one of the tiny passage ways has an obstruction somewhere. Does this sound like I'm looking in the right direction?
Other things I'm wondering about:
Could bad stator cause something like this? I don't see drip marks or anything coming down from under the flywheel.
Could bad rectifier cause this? I'm pretty sure its bad since I don't see any charging happening on the amp gauge.
Could something in the intake manifold or bad reeds cause something like this (it looked clean in there when I pulled the carbs so I didn't think there was any reason to remove the manifold. I'm a little concerned due to the earlier mentioned mud daubers and fire ants though).
If there was a bad wire or bad ground, would the engine be running so good at high speed?
Could cloged check valves on the intake manifold cause a symptom like this? I broke one and replaced it, the original seemed really dirty. I know I should pull the rest of them and attempt to clean them but they were made of plastic back then and I'm concerned with breaking them. Could blockages cause bad idle?
So far I've done the following to the engine: removed probably 20 mud dauber nests from engine and carb, installed new starter (was missing), 2 new power packs (1 was bad), new coils (from my blown engine), new seals on lower unit, new impeller, rebuilt carbs (one was full of mud dauber nests), replaced all fuel lines with new ethanol resistant lines), new primer unit, verified great compression (125 psi on all 4 cylinders).
I ran her for the first time today. The engine ran perfect above 1500 RPMs. I took her to 5100 RPMs and it sounded tight, as good as a brand new engine. Perfect power through all RPM ranges. Temperature on the heads is 140 degrees after running it WOT.
Idling is another story though. If I run it hard it idles good for a minute or 2. The rest of the time it stumbles, it sounds good for 2 or 3 seconds and then dies abruptly. When starting it usually fires up fast and then may try to die 2 or 3 seconds later. Hitting the primer can help to keep it going.
I'm leaning toward a carburetor problem, especially since there had been a mud dauber nest in one when I rebuilt it. There were also fire ants in there eating the mud dauber larvae from the nests. All jets were removed and cleaned before but I'm thinking maybe one of the tiny passage ways has an obstruction somewhere. Does this sound like I'm looking in the right direction?
Other things I'm wondering about:
Could bad stator cause something like this? I don't see drip marks or anything coming down from under the flywheel.
Could bad rectifier cause this? I'm pretty sure its bad since I don't see any charging happening on the amp gauge.
Could something in the intake manifold or bad reeds cause something like this (it looked clean in there when I pulled the carbs so I didn't think there was any reason to remove the manifold. I'm a little concerned due to the earlier mentioned mud daubers and fire ants though).
If there was a bad wire or bad ground, would the engine be running so good at high speed?
Could cloged check valves on the intake manifold cause a symptom like this? I broke one and replaced it, the original seemed really dirty. I know I should pull the rest of them and attempt to clean them but they were made of plastic back then and I'm concerned with breaking them. Could blockages cause bad idle?