Momentary loss of RPM and bilge pump activation.

[Billtex2000]

A few days ago cruising at 7000rpm, my port engine dropped to about 5000rpm for 3-4 seconds and came back up to 7000. I thought maybe I sucked something in through the intake and the impeller pushed whatever it was out. What concerns me is that a few seconds after that, my bilge pump came on and ran for 10-15 seconds while I was still on plane. My pump NEVER comes on unless the boat has been sitting in the slip in heavy rain. Since that event, the pump has run and pumped out about a gallon of water or so each day when I get underway when the boat gets up on plane, rather than when the bow is up and reaching plane! The engine has run normally since that single event. Engine compartment is bone dry other then the area down around the bilge pump. Checked the cleanouts and there's nothing there. Everything I can see under the cleanout tray appears dry and normal. Is there anything that would cause a sudden momentary loss of RPMs followed by a bilge pump activation/leak?

 

[Julian]

My guess is it was simple coincidence that these things happened at the same time.

Typically when you give it gas, water moves to the back of the boat. Since these (older) boats don't have float switch bilge pumps, the timing of when the pump comes on is not related to the water level and timing of your acceleration, but rather the timing of the every 3 minute water check the bilge pump does (thats how back pressure pumps work...they cycle every 3 minutes).

 

[Billtex2000]

My guess is it was simple coincidence that these things happened at the same time.

Typically when you give it gas, water moves to the back of the boat. Since these (older) boats don't have float switch bilge pumps, the timing of when the pump comes on is not related to the water level and timing of your acceleration, but rather the timing of the every 3 minute water check the bilge pump does (thats how back pressure pumps work...they cycle every 3 minutes).

I actually have a float switch installed, and since that event, I've been taking on about 3 gallons overnight each night that the boat is sitting in the slip. Could a hose or seal or something have blown that would have caused the sudden RPM loss, resulting in a leak?

 

[Julian]

I actually have a float switch installed, and since that event, I've been taking on about 3 gallons overnight each night that the boat is sitting in the slip. Could a hose or seal or something have blown that would have caused the sudden RPM loss, resulting in a leak?

Have you replaced the scupper valve?

 

[Billtex2000]

Having it done as we speak. I'm hoping it's a crack there and not something related to the loss of RPMs.