Back To Top

Fuel Problems When Rolling

Yachting Home Forums All things Technical Engines Fuel Problems When Rolling

  • This topic has 6 replies, 6 voices, and was last updated 7 years ago by Anonymous.
Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
  • #16361

    I am looking at purchasing an older NC33 (pre-poop deck). One fuel tank has been replaced by a bladder which on this trial was low but not empty.
    On short steep beam sea, at low revs, where the boat was rolling uncomfortably the engine faltered, then a little later quit.
    Is this a common problem? Would anyone speculate as to the most likely cause and remedy?
    Thank you


    This is entirely abnormal.

    Engine failing out may be due to air intake, easily though temporarily solved by bleeding the high pressure pump.

    Air ingress will happen on that part of pipes where succion occurs. That is betzeen the tank and the low pressure fuel pump.

    When I acquired my NC33 back in 2011 I suffered from comparable problem whenever sea was rough.
    I found out monthes latter that fuel pipes where not 100% waterproof and air bubles could leak in.
    This appeared due to filtering equipments (decanteur) that were a bit loose and their motions at rough seas put strains on the junctions and led to air intakes.

    In the interim I mostly solved the problem by wrapping every nut or junction with autovulcanizing rubber.

    From time to time I check that all those filtering elements are strongly tighgtened to their place.

    Hope it helps,
    Yves (Naïla, NC33 1978)


    Thanks for your reply Yves. I will check those things.

    Vic Crowhurst

    The tanks in 33’s are baffled across (side to side) and reduce forward/backward movement of fuel. It may be that with the rolling momentum in the fuel shifted the top level below the take-up pipe even though it is in a recess well bottom mid aft of the tank. This lets air in, initially the engine can draw bubbles through with just a temp splutter but if a large enough air bubble ingresses, it stops. I found keeping the tanks well filled helped. If you can re- route to reduce the roll and suffer more pitch, or raise some mainsail to dampen the roll, that will get you home.
    Vic Crowhurst, Nautilia 33, Nautinto 37

    David Babsky

    Oh: how lovely to see Dr Vic in the reply above! We have Dr Vic’s previous Nauticat, and love her! (..and Dr Vic, of course!)

    A problem which I found fairly early in our ownership of Nautilia was that in “..short steep beam sea..” or similar bouncy conditions, muck from within the fuel tank(s) (..though Dr Vic had kept them scrupulously clean!..) – or in that bladder – gets all stirred up and can easily clog one, or more, fuel filter(s). So always have extra filters on hand, and – as Dr Vic says – have fuel tank(s) well filled, so that the end of the fuel tube is always well immersed, whatever the boat’s angle.

    If the low-pressure lifting fuel PUMP diaphragm has not been checked for a year or three, do check that the rubber diaphragm has no cracks or holes and hasn’t perished.

    I found that when our fuel tanks showed ONE THIRD or less full, the fuel inlet pipe could easily suck in air, and that there wasn’t a USABLE one-third-of-a-tank of fuel still available, and so I never after let them get lower than one HALF full. (Discovered that during entrance to Dartmouth, among the rocks(!) ..and then again with Dr Vic on entering Dover at night!)

    I also removed both fuel-gauge senders/sensors, and replaced them with much more reliable and accurate vertically moving floats, and calibrated those so that I knew that the readings on the electrical fuel tank gauges were properly accurate. (The originally-installed senders used a hinged arm and a fragile carbon electrical track on their arms, and the carbon had cracked, so that readings were unreliable. I installed two more reliable vertical “reed switch” senders similar to these: )

    I don’t know how “common” a problem this is, but I’d say (1) be sure to put ‘Marine-16’ or similar diesel-bug biocide in your tank(s) each year; (2) be sure that you know how ACCURATE your fuel gauges are; (3) keep tanks close to FULL, if poss, so that the inlet suction pipe doesn’t suck in air when the boat heels; (4) check at least annually your fuel filters and fuel pump diaphragm.


    3 years ago I sailed my 43 year old NC33 ZARZUELA across the Channel from Portsmouth to St. Vaast in near gale force Easterly winds, engine running to ensure we made the tide to enter St. Vaast. One mile off at 0400 the engine stopped on a lee shore. French signal station helped issue a Pan Pan and we were rescued by the SNSM Lifeboat who towed us into the Marina.

    ZARZUELA has fuel tank air vents below the maindeck level and the severe rolling during the crossing dipped them underwater to suck in the water (20 ltrs. of water in each tank!).

    I was advised to have the vents lifted above deck level, as some boats have, but due to costs have not done so yet.



    Every mentioned reason for an engine to stop running is mentioned above and true but….

    1.air coming in:structural and not accasionally in bad weather !
    2.water in diesel:common problem but with good(ex. separ filters) wiich are doubled and in case off visual water exxess in the bowl easely changed with valve settings:problem fixed !
    3.clogging filter elements with dirth and or algea (same soltion as nr 2
    good practice also when you planned a trip in bad weather make Always shure both your tanks are FULL at the start,that minimises diesel stirred up en clogging and or water wich are on the bottom of your tank are mixed with the diesel

    note,when you have only one filter and you have to clean it from dirt and or water ,then you must have aan handmpump installed n your circuit to fill the filter again!!i have an recipient with some diesel to fill it up,you do not want to bleed the entyre feul system from air!!!if been there …and also 2 filters,indeed after you have a problem with your engine in bad weather once you make damned sure you have two of them!!!

Viewing 7 posts - 1 through 7 (of 7 total)
  • You must be logged in to reply to this topic.