I have an NSF-5B that was converted to 6HP with a carb. It has been running flawlessly for a year.
Was running it over the weekend and after about 15 minutes of almost full throttle (about 5200 RPM) I noticed it miss a couple times. A few minutes later it started losing power. We were almost at the destination, so I dropped down to about 3000 and ran for another 3-4 min, then when down to just over idle as we were approaching the anchorage. Before we got there, the engine quit. It stumbled a couple times just before it quit. I tried to restart and noticed the oil lamp blinking crazy, so I thought I might actually be low on oil... as I hadn't put any in for months (didn't seem like it ever needed it). It was low on the dipstick, so I put a little in, but being careful to NOT overfill per Paul's previous guidance on here. Ran it again on the way back, but due to lake conditions didn't go as fast. As we were approaching the marina I noticed a few more misses, but it made it back to the dock ok. It was one of the hottest days we've had this year.... ~90.
Today I took it out on the lake today (and it was hot again). I ran it back and forth for a bit and started to notice an occasional miss but also a hesitation at mid-throttle when throttling up. Took a while but it finally died. As it was dying, I was careful to observe the oil light and it DID NOT light at all. When I tried to pull-start right away, the oil light was blinking like mad, just like the day before. I popped the top and checked over everything and nothing seemed amiss. The coil and CDI were hot, but not more than you'd expect being connected to the block or 1" from the head. I had a cup handy, so I poured some lake water over both for a minute or so. Pulled the cord and it started up. Ran around again till it stopped and repeated the exercise and it started up again. The oil light was not blinking or lit before it died, but blinking when I tried to pullstart right away.
If I was foaming the oil, wouldn't the low oil pressure light blink before the engine would die?
Is it possible the oil pressure switch is bad? This would make sense for the blinking light when trying to start, but does not explain why it dies in the first place. I didn't think of it while I was out there, but I should have disco'd the oil switch wire and tried to start it.
I'm wondering if it's a heat-related CDI issue, but I'm not familiar with different CDI failure modes. Is this something that anyone has seen before? However, since the oil light is blinking, I don't know how that could happen without the oil switch making contact.
Suggestions? I do have the real service manual and can do all the resistance checks but wonder if this would show anything unless the CDI is heated to temperature. This unit has the exciter coil and pulser coils, and I can check those too (but have the same heat-related concern).
Was running it over the weekend and after about 15 minutes of almost full throttle (about 5200 RPM) I noticed it miss a couple times. A few minutes later it started losing power. We were almost at the destination, so I dropped down to about 3000 and ran for another 3-4 min, then when down to just over idle as we were approaching the anchorage. Before we got there, the engine quit. It stumbled a couple times just before it quit. I tried to restart and noticed the oil lamp blinking crazy, so I thought I might actually be low on oil... as I hadn't put any in for months (didn't seem like it ever needed it). It was low on the dipstick, so I put a little in, but being careful to NOT overfill per Paul's previous guidance on here. Ran it again on the way back, but due to lake conditions didn't go as fast. As we were approaching the marina I noticed a few more misses, but it made it back to the dock ok. It was one of the hottest days we've had this year.... ~90.
Today I took it out on the lake today (and it was hot again). I ran it back and forth for a bit and started to notice an occasional miss but also a hesitation at mid-throttle when throttling up. Took a while but it finally died. As it was dying, I was careful to observe the oil light and it DID NOT light at all. When I tried to pull-start right away, the oil light was blinking like mad, just like the day before. I popped the top and checked over everything and nothing seemed amiss. The coil and CDI were hot, but not more than you'd expect being connected to the block or 1" from the head. I had a cup handy, so I poured some lake water over both for a minute or so. Pulled the cord and it started up. Ran around again till it stopped and repeated the exercise and it started up again. The oil light was not blinking or lit before it died, but blinking when I tried to pullstart right away.
If I was foaming the oil, wouldn't the low oil pressure light blink before the engine would die?
Is it possible the oil pressure switch is bad? This would make sense for the blinking light when trying to start, but does not explain why it dies in the first place. I didn't think of it while I was out there, but I should have disco'd the oil switch wire and tried to start it.
I'm wondering if it's a heat-related CDI issue, but I'm not familiar with different CDI failure modes. Is this something that anyone has seen before? However, since the oil light is blinking, I don't know how that could happen without the oil switch making contact.
Suggestions? I do have the real service manual and can do all the resistance checks but wonder if this would show anything unless the CDI is heated to temperature. This unit has the exciter coil and pulser coils, and I can check those too (but have the same heat-related concern).