I've had a couple of concerning incidents in the last few days with our Yanmar
3GM30F losing power. Briefly, not long after starting up and putting a load on, the engine
will drop 300-500 RPM
, in or out of gear
, intermittently. Advancing the throttle has no effect, although lowering it will lower RPMs as expected. The drop was severe enough to kill the engine
once. In both cases, within about a half hour, the problem disappeared without intervention after limping along for a bit.
I have pulled up the other threads on power loss but this appears to differ from those in that it is intermittent, not constant. While the power is dropped, I'm not producing smoke of any sort. The engine returns to the full rated power at some point... or it has so far! So I don't think I'm looking at a prop issue or exhaust
or fouling problem.
My suspicion is fuel
flow so I've changed the filters out, but they did not appear particularly crudded up. On one of the occasions, we had been in some pretty bumpy stuff immediately before starting the engine so I was thinking perhaps tank crud got stirred up, but the other time, we hadn't hardly been shaken at all. And we had been lumped around pretty good on an intervening day without experiencing the problem at all.
We're in some moderately remote
territory right now (with very infrequent internet
access; my apologies if I am not able to reply immediately) getting ready to get into even more remote
territory, so I just want to make sure I've covered my bases with this before I get outside the realm of mechanics and engine shops. Are there any other likely causes for this sort of behavior besides fuel
In particular, I'm wondering if it could have anything to do with not warming the engine up enough before putting it under load. Since the problem has, so far, disappeared within 30 minutes, and since it happened, on both occasions, when we had not spent very long warming up, that has crossed my mind... but so far, I haven't ever heard anyone suggest that as causing such power problems. I'm sure it hasn't happened every time we haven't warmed it up sufficiently, but I've only got these two episodes to look at for similarities so I'm grasping at straws a bit.