My O'day 302 has a 2GM20F. As I was motoring along at about 2500 RPMs. Suddenly the RPMs dropped to about 1500 and the speed dropped as well. I put it in neutral and the RPMs were normal. I sailed near my dock and started the motor to dock and everything worked normally. This is the second time I have had this issue. Any ideals?
Yanmar 2gm20f issue
- Thread starter Ryan R
- Start date
One (of many) possible causes is a clog in the pick-Up tube screen in the diesel tank. Needs to be checked and cleaned periodically. The behavior you described would manifest itself typically at higher RPM but not at low RPM. Filters are obviously another possible cause but less likely and more obvious.
Another item to check is the mixing elbow. Did the exhaust turn black and were you leaving a sheen on the water when the RPMs dropped?
Is that (Black stuff in the exhaust) indicative of a mixing elbow issue?
I get that, but only when run the RPMs over 3400. I also have a 2GM20F.
Greg
When my mixing elbow clogged, I had lots of unburnt fuel in the exhaust.
Also, look carefully for a plug in your fuel tank vent. If the problem happens again, loosen the fuel fill cap .. that would vent the tank .. if the engine runs normally with the loose cap, the tank vent is plugged. If no change then fuel pickup tube in tank or a fuel filter plugging.
Good luck.
Good luck.