Loss of revs

[Paul123]

Hi all. Had my Bavaria 33 with a D1-20 engine for 2 years and the problem for almost as long. It is this. I motor out for 20 minutes to go sailing , all fine never had a problem. I sail for a while then go to motor back. I regularly then loose revs or the engine stops completely. I can sometimes keep it going by pumping the primer, indicating low fuel pickup I presume but sometimes I just wait an hour and it all works ok.
I’ve had mechanics on the boat several times but they have been unable to fault the engine as it always goes perfectly for them. Initially I found diesel bug in the tank and filter, thought I had solved it but it continues. In desperation I now feed the engine from a new tank with new fuel lines. I have fitted a new racor filter and the fuel and filter are clean, no water, but the problem reappeared last sail.
Out of ideas as are the mechanics it seems. Ps fuel pickup is fine.

[Stu Jackson]

Fuel Starvation and The Obscure Check Ball Valve
https://c34.org/bbs/index.php/topic,10681.0.html
and
https://forums.sailboatowners.com/th...l%20Starvation

[Paul123]

Thanks for the info though I don’t think it applies in this case. I’ve only run on the racor for less than 1 hour. Fuel is new, cartridge is clean. Plus I had the same issue with the original filter a Delphi.
PS Can anyone tell me if I should be able to pump the primer while the engine is running or should it be firm?

[Compass790]

Still think its a fuel issue but could be an air issue, dont know how its happening.. You say you've eliminated filters, pickup & tank but try clear fuel lines to see if there are any bubbles. Not sure about primer pump. Have you checked tank vent?

[fxykty]

Originally Posted by Compass790

Still think its a fuel issue but could be an air issue, dont know how its happening.. You say you've eliminated filters, pickup & tank but try clear fuel lines to see if there are any bubbles. Not sure about primer pump. Have you checked tank vent?

This.

Most likely an air leak. An obvious sign is if you see bubbles in your pre-filter when you pump the primer bulb.