Engine cutting out in rough seas

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system

Engine cutting out in rough seas

Postby Belanich » Sun Oct 08, 2017 7:09 pm

Hi All,
I have a F36/38 that was repowered with a Yanmar 40hp. We were motoring out of Milford Ct on our way back to Mount Sinai in ~6ft seas, 25-30kn winds when the engine cut out after about an hour of motoring. It started right up then cut out again a couple of minutes later. It started right up again and we put up the sails. When we reached the harbor the engine started right up and ran perfectly all the way to the mooring.
I doubt the problem is a clogged filter because it ran fine in the harbor. Is it possible that air was sucked into the fuel line? Has anyone else had this problem with this oddly shaped fuel tank? BTW the fuel gauge on top of the tank registered 1/3 full.
Michael Belanich
Dolcetto F38
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Re: Engine cutting out in rough seas

Postby BillSmith » Mon Oct 09, 2017 12:39 am

Will relate what we found to be our problem that rings similar to your description.

The fuel pickup tube in our boat HAD a small screen to pre-filter debris that might be residing in the fuel tank. When you run the engine hard, that screen clogs and starves fuel to system. Engine dies, fuel demand lessens and debris drops out of tube, clearing for another start. Bottom line, fuel demand changes the dynamics of filtering.

If at idle or low RPM, the fuel demand can be low enough that enough fuel pressure is achieved.

Also, the rougher seas stirs up more debris in fuel tank, thus more floating pieces to clog that screen.

Recommend you open access point on fuel tank that should have an uptake tube. Remove it and tap it on a paper towel. Or blow it out like a clogged straw.

We removed the little screen and had the fuel polished. No problems since. Racor filter is enough to separate any gunk.

Start with checking how 'dirty' your fuel might be and whether you have that screen in your pickup tube.
Bill & Carole Smith
Freedom 35 Pedrick
SweeTART
Coyote Point
San Mateo, CA
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Re: Engine cutting out in rough seas

Postby jdpandlp » Mon Oct 09, 2017 6:28 am

Had a similar issue after having a generator installed on White Wings. After a few months the main engine acted fuel starved. Would run a low RPM but would not operate under load. In my case the screen on the pick-up tube had already been removed but as I disassembled the fuel lines I found that the connector at the top of the fuel pick-up tube was packed with cotton thread. My guess was that during the installation of the fuel pick-up for the generator the cleaning rags were fraying.
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Re: Engine cutting out in rough seas

Postby mike cunningham » Mon Oct 09, 2017 11:56 am

And one more similar experience. I was motoring offshore and engine cut out, started it again, cut out again. Did this once or twice more and had to troubleshoot as I was appraching San Francisco entrance with no wind. After a lot of TS found that blowing into the fuel tank uptake cleared the problem. Once home I cut an inspection plsye into the aluminum tank. An essential mod IMO and found a few small chunks of a parrifin like substance rolling around near the uptake tube. I cleaned this up and all was good. Couple of lessons learned on that one.
1. Make sure you know how to bleed the fuel system know where each Port is and what size wrench fits.
2. Fuel Tank inspection port is invaluable.
3. I have heard removal of uptake screen is a good idea. Mine was gone. Not sure on this one. For OP seems like screen was problematic, primary filter would have cleared the fuel. In my case a screen probably would have helped but may have changed my mind on an inspection port. Anyone have any thoughts on the scenic yea or nay?
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