Two Filters, Three tanks, One engine.

Discussion in 'Boats, Motors, Trailers and Towing Rigs Forum' started by gungadin, Dec 13, 2017.

  1. gungadin

    gungadin Well-Known Member

    I have recently replaced my main two stroke engine and two stroke kicker with one four stroke engine. I used to run two tanks for the main, going through one water separator/filter located on the starboard side of the transom, and one tank for the kicker through another water separator/filter, mounted on the port side, both 10 micron. I am now going to run all three tanks for the one engine. The two tanks on the starboard side will go through both the filters before going to the engine, while the port side tank will only go through the filter on the port side before going to the engine.
    After all that preamble this is my concern. At this time I have not installed any shut off valves. Will the engine draw from both the port and starboard tanks if i don't install separate shut off valves? My instinct says they will, however if the fuel follows the line of least resistance then perhaps the engine will only draw from the port side tank as it only goes through one filter.
    If anyone else has done this, if so what did you find? Even if you have not done this, what can you speculate will happen.
  2. Wild Bill

    Wild Bill Active Member

    It will draw from whatever is easiest, any tank starts sucking air and it won't matter how much fuel is left in the others.
    With 3 tanks it might be easiest to put a valve on each line. Selector valves easy to get for 2 tanks.
  3. Fixit

    Fixit Well-Known Member

    If it was me I’d have a selector valve for the port/stb main tanks or some way to equalize the two... maybe a line between the two?
    then use the third (presumably smaller?) as a reserve tank
  4. Wild Bill

    Wild Bill Active Member

    Bottom feeds and equalizer lines mean any leak in the connections ends up in the bilge. Won't get past a surveyor and not safe.
  5. gungadin

    gungadin Well-Known Member

    Sorry I should have pointed out that they are portable tanks. At this point I think I will put a ball type shut off valve on the inflow side of each filter housing. I think doing it this way will prevent any fuel being sucked from an empty tank and the filter not being used. Does this sound right?
  6. ratherbefishing

    ratherbefishing Active Member

    I would want some king of shutoff as this allows you to isolate a tank if there was a problem, if you wanted to trim the ride, etc...
  7. Wild Bill

    Wild Bill Active Member

    If they are all hooked together once one tank is empty the result is the engine will not run so yes just a ball halve on each line will suffice.
    gungadin likes this.
  8. gungadin

    gungadin Well-Known Member

    Done, Thank you.

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