Sea Sled madness. It’s in my brain.

Discussion in 'Fiberglass and Composite Boat Building' started by DogCavalry, Nov 11, 2019.

  1. baeckmo
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    baeckmo Hydrodynamics

    Now hold on, that fuel filter is NOT to be cleaned, it is a throwaway exchange filter cartridge!!!! You have had water in the fuel, enough to create rust (probably on the filter bowl inside). The reddish colour of the fuel sample is an indicator for this. An attempt to clean the cartridge will almost certainly lead to further contamination of the downstream components, which already may have seen some damage from the water in fuel.

    The "vapor separators" come in different shapes, and this is actually a combined fuel cooler/constant level suction bowl. It serves to give the high pressure pump the required inlet pressure. There should be a float inside, like in a carburetor, with a little needle valve. Check that this valve is moving freely and not sticking in any position.
     
  2. DogCavalry
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    DogCavalry Senior Member

    Understood
     
  3. baeckmo
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    baeckmo Hydrodynamics

    Fine, before doing anything else on the engine, fit a new filter cartridge!
     
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  4. fallguy
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    fallguy Senior Member

    I think you are getting lotsa good advice.

    Any chance any of this contamination is related to the tank refurb?

    Shoot a half pint of gas from the tank unfiltered into a white bucket and see if it looks bad. You want to eliminate it from future concern. If the gas looks good and is clean; back in it can go. If it ain't....

    Just cause if the tank has been getting a good sloshing now under some heavier seas; it could have been washed inside. So easy to check.
     
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  5. DogCavalry
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    DogCavalry Senior Member

    Tank dirt has been a concern. It was a used tank after all. That's part of why I added the second filter. The extra in and out connections also make it easy to connect in an emergency tank, or run a second outboard from the main tank.
    There's no restriction after that external filter separator though. Today as well as getting the new filter I'll get a fuel pressure gauge. And a new voltmeter because another mechanic pointed out that low fuel flow can come from bad signal to the injectors.
     
  6. fallguy
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    fallguy Senior Member

    I was wondering if the tank was used for diesel in a former life even..or if that color could be from welding contaminents or scorching washing out..

    Seems odd for sure.

    Did you use brand new fill and supply and vent lines?

    Does your vent line have a drip loop?

    All things to ponder with a dirty filter and low hours. A dirty mess is relatively solvable.
     
  7. baeckmo
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    baeckmo Hydrodynamics

    Fallguy, please note that the primary filter was holding clean fuel, the coloured fuel and the residues came from the secondary. Welding "soot" from aluwelding with MIG is normally black (it's the magnesium that burns off if handled wrong, or welding in the open winds). Sometimes there could be a red-ish layer of bacteria in tanks holding puddles of brackish water, but I think this tank shape was remodeled slightly. Can't think of an aluwelder that would not clean a fuel tank before welding; it is simply a nono!

    In "the old days" gasoline was red, but if you see red gas today, it has passed through (or past) something rusty; nothing odd there.
     
  8. fallguy
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    fallguy Senior Member

    oh, I missed that the primary filter was clean

    so, is mixed fuel leaking back down?

    Then what are the black bits in the secondary that are not in the primary?

    Sorry, but I have never seen fuel flowing back and the clean side of the filter dirty, so something is very confusing for me here.

    I don't know how the fuel mixing system works, but I have to believe it would not have a backflow prevention.

    What is rusty making things red?

    etc...

    kindest regards @baeckmo ....
     
  9. DogCavalry
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    DogCavalry Senior Member

    The small filter immediately before the high pressure pump is old. Original to the engine. All my lines are new. The mess I poured from the old filter. I suspect it's from the original boat. Not mine.

    However... She ram perfectly the first six weeks. Then we had a 1 day monsoon. After that, progressively worse. Maybe a coincidence
     
  10. DogCavalry
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    DogCavalry Senior Member

    @baeckmo , plugs per your direction. Three from the port side. IMG_20221125_172803165_HDR.jpg IMG_20221125_172812908_HDR.jpg IMG_20221125_172826692_HDR.jpg
     
  11. DogCavalry
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    DogCavalry Senior Member

    Ran the fuel pressure gauge on the high pressure port of the circulation pump. On key turn pumped up to 40 psi, then pump stopped and dropped instantly to 30 psi.
     
  12. baeckmo
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    baeckmo Hydrodynamics

    Plugs...just what I expected; heavy coke deposits and it looks like some gaps are bridged; no spark there! Get new ones, and be careful to install them correctly. Mark the insulator body with a line corresponding to this gap, so you can see where it is positioned ok. The side with open gap must face the injector.

    Even if the engine temp is kept ok by the cooling water thermostat, the plugs don't reach normal working temperature (necessary for tip cleaning) when idling all day.
    Until prop issues are fixed, you have to load the engine at least once a day by running a "bollard pull"-session. Stem to pier or pole and increase throttle until there is a decent working load, say 4000 rpm at least, on the tach. Run for minimum five minutes, then let idle and cool down for two-three minutes before shutting down. Then, DO NOT tilt the engine until the power head is cold, to avoid oil spill and vapour blow-off.
     
  13. fallguy
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    fallguy Senior Member

    This is so interesting.

    May I ask just one thing?

    How does the engine know if it is revved in neutral or in gear OR what is the difference? Or is it simply that opening the throttle up to 4000 in neutral for 5 minutes is bad for the engine? Not enough cool water, etc. I'd not enjoy doing it...

    It is probably be hard to do a bollard pull for most people at home, so temptation is to rev in neutral.
     
  14. DogCavalry
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    DogCavalry Senior Member

    @baeckmo - clear direction. I'll do that. Can I clean and reinstall them now, strictly as an aid to further troubleshooting?

    @fallguy - good question. Since I live in a fjord, and Serenity's bow was literally designed for pushing against a cliff, I'll do exactly that. But can the impeller draw in sufficient water without flow from propeller action?
     

  15. fallguy
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    fallguy Senior Member

    I'd make sure a failure of the line or any failure means you head to sea..

    Maybe it is just my memory of a few too many runaway snowmobiles.

    Another thing about running hard near shore or against a rock is mudding up the lu, delaminating the hull.

    Maybe stern tie to a couple trees? Or one with a bridle..
     
    Last edited: Nov 26, 2022
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