I have a real puzzler, that has cost me a butt load of time,
money, and some hair. I have a 1985 Yamaha 115 precision blend outboard that has the strangest symptoms. Firstly, I am a 45 year old auto-mechanic that has been spinning wrenches for 28 of them, so I am no stranger to mechanical systems. The outboard sat in a friends garage for 15 years, so I knew I would have some carb work. I rebuilt both carbs, replaced the fuel pump, fuel lines, removed & cleaned the fuel tank, cleaned out both the remote oil tank and the on-motor oil tank, changed sparkplugs, changed waterpump, resealed lower unit, flushed trim & tilt fluid.
This particular model has 2 Teiki carburators on it. After accomplishing all of this work with the help of a seloc manual, I took the boat out on the local lake for a test & tune. I got it to idle decent, but as I brought the throttle up over 1800 rpms, it would start to misfire and just die. I discovered that I could manually flutter the electric choke and get it past this point to full throttle where it ran fantastic. I ran it at full throttle across the lake for almost 45 minutes, never missed a beat, green light on the console says all is ok. When I try to back off full throttle to about 4000 rpms, it starts to sputter, misfire and die unless I manually trigger the electric choke, and that certainly smooths it out temorarily. This tells me it's lean from 1800rpms to 4000, but, low speed and full throttle is fine. I figure I must have missed something in the carbs, so I pull them off and soak them in an agitating carb tank over night, then boil them in a 50/50 mixture of carb cleaner & water for a couple of hours before blowing them out and reassembling them. I put them back on, SAME PROBLEM! I decided to check my spark intensity, and found a weak coil, After replacing all 4 coils I have the SAME PROBLEM! All 4 Cyls compression is right at 140PSI, and there is no smoke
or other evidence of excessive oil burning. What makes this even weirder is that when I pull and check the spark plugs, they are always fuel fouled..
Anyone gotta clue? I'm ready to toss a match in it's general direction..
Phil....
money, and some hair. I have a 1985 Yamaha 115 precision blend outboard that has the strangest symptoms. Firstly, I am a 45 year old auto-mechanic that has been spinning wrenches for 28 of them, so I am no stranger to mechanical systems. The outboard sat in a friends garage for 15 years, so I knew I would have some carb work. I rebuilt both carbs, replaced the fuel pump, fuel lines, removed & cleaned the fuel tank, cleaned out both the remote oil tank and the on-motor oil tank, changed sparkplugs, changed waterpump, resealed lower unit, flushed trim & tilt fluid.
This particular model has 2 Teiki carburators on it. After accomplishing all of this work with the help of a seloc manual, I took the boat out on the local lake for a test & tune. I got it to idle decent, but as I brought the throttle up over 1800 rpms, it would start to misfire and just die. I discovered that I could manually flutter the electric choke and get it past this point to full throttle where it ran fantastic. I ran it at full throttle across the lake for almost 45 minutes, never missed a beat, green light on the console says all is ok. When I try to back off full throttle to about 4000 rpms, it starts to sputter, misfire and die unless I manually trigger the electric choke, and that certainly smooths it out temorarily. This tells me it's lean from 1800rpms to 4000, but, low speed and full throttle is fine. I figure I must have missed something in the carbs, so I pull them off and soak them in an agitating carb tank over night, then boil them in a 50/50 mixture of carb cleaner & water for a couple of hours before blowing them out and reassembling them. I put them back on, SAME PROBLEM! I decided to check my spark intensity, and found a weak coil, After replacing all 4 coils I have the SAME PROBLEM! All 4 Cyls compression is right at 140PSI, and there is no smoke
or other evidence of excessive oil burning. What makes this even weirder is that when I pull and check the spark plugs, they are always fuel fouled..
Anyone gotta clue? I'm ready to toss a match in it's general direction..
Phil....