[holiday3900]

We were just on a long run from Charlevoix to Southwest Michigan. Boat ran fine, but higher than 2100 RPM and at plane in (especially in 3-5 foot seas) i noticed the aft bilge light would come on and run for about 1-2 minutes at a time. I checked everything including bilge before starting out....only a drop or two of water under the engine all else totally dry, and no signs that there was water previously. Manual bilge runs fine with light on/off as it should, so I've somewhat ruled out light/switch malfunction In heavy seas is this common? I checked strainers and they seem to be fine. Anything i should look for in terms of where water might be coming from? Thanks owners.

[Uhehner]

We were just on a long run from Charlevoix to Southwest Michigan.  Boat ran fine, but higher than 2100 RPM and at plane in (especially in 3-5 foot seas) i noticed the aft bilge light would come on and run for about 1-2 minutes at a time.  I checked everything including bilge before starting out....only a drop or two of water under the engine all else totally dry, and no signs that there was water previously.   Manual bilge runs fine with light on/off as it should, so I've somewhat ruled out light/switch malfunction  In heavy seas is this common? I checked strainers and they seem to be fine.  Anything i should look for in terms of where water might be coming from?   Thanks owners.

Is the pump just coming on or is it really pumping water?  Just look over the side.
Check the rudder post packing.  At rest the packing is above the waterline. On plane the props put water pressure on the packing. Tape a paper towel around the post. If it's wet after a run you have found the problem.
Capt. George

[ReelMagic]

Not sure where the aft bilge pump is on your 39 Sovran but on my 2003 38 Open it's near the transom and when I accelerate from an idle to cruise speed the pumps comes on for 20-30 seconds. This due to the small amount water in the bilge that runs aft. Not enough to pump but enough to cause the pump to come on. Had the same problem on my 1997 31 Open.... Pump always goes off after 20-30 seconds M2C

[holiday3900]

Update and conclusion -- a week later running the boat, coming back into the harbor we smelled diesel fuel. Got back to dock and found a significant leak. A small leak because of a bad fitting turned into a big one when the line completely came loose. The bilge coming on so frequently was the diesel fuel accumulating, then when on plane, rushing to the aft bilge. We shop vac'd the remaining diesel out. Glad we caught it before a catastrophe or any more diesel was pumped out.