3gm30f is acting up. I've only owned the boat for a few months and the diesel
ran tip top until very recently. Always started within a second or two of cranking her over and never more than a couple seconds of smoke at start up and then none visible afterwards. In the last couple of weeks some changes have come over her. Symptoms:
- On 4 occasions she has taken 4-5 seconds to start and then has idled really roughly with lots of vibration at low RPMs (500ish) and then died. When I turn her over again she has caught, coughed, and then run smoothly after puffing out a bit of smoke. This has only happened first thing in the morning after at least 12 hours since the last run. She always starts and runs smoothly for the rest of the day.
- She is putting out a bit of white smoke on some occasions. Not a lot, but more than she ever did before. Yesterday it was everywhere from idle to 2500 rpm
. Today, hardly a hint of smoke however.
- If I reverse under load, primarily when setting the anchor
, she is hard pressed to go over 1500 RPMs and puts out black smoke in the process. When I throttle back down to idle she kicks out a bit of black crap in the cooling water
. This is not a new problem, however, and has been the case as long as I've had her. The boat has a 3-blade feathering prop, if perhaps that has any relevance to the difference in reverse versus forward.
One theory about the starting problem:
The batteries are not isolated properly (previous owner) and on occasion I forget to set the selector switch to the right position for starting and then charging
. Sometimes I accidently partially drain the engine battery
while using house electronics
. I a,m guessing the engine
batt has suffered due to this. Perhaps if it has been sitting idle overnight and is not in a full state of charge, it's cranking amps are low and cannot spin the diesel
quickly enough, hence the 4-5 seconds to start. During that process, unburned fuel
is gathering in the cylinder, causing the sputtering when it finally catches. Once the cylinder has been cleared of fuel
, she restarts properly. Any merit to this theory?
I don't think it's bad fuel, as we've got brand new filters in place that are clean and I would imagine this problem would continue beyond start up. I haven't checked the air filter yet, though. Is that a possibility?
All ideas are welcome. I'm currently in St. Kitts and will sail to Guadeloupe
over the weekend in hopes of finding a Yanmar
technician in Pointe a Pitre. I'd rather avoid him if it's something simple though!