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2006 BF90A Cylinder Problem

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  • 2006 BF90A Cylinder Problem

    First time needing some help with a problem with my Honda. I have a 2006 BF90A. I was having what I thought might be fuel problems. But now I am stumped due to the following:

    Motor is not running on all 4 cylinders. At first it was 2 and 3 not working and thought maybe a coil. But then it jumped to 2 and 4 not working. Then it went to 1 and 3 not working. I am thinking this must be electrical but I am not sure as to where to start checking.

    Any help would be greatly appreciated.


  • #2
    I will give you a full update of what we have done so far to reach where we are:

    Drained all fuel and put in 91 octane today. Also changed out fuel filter and tested the fuel pumps (by pushing in the bar to make sure it is staying hard as well as checking for leaks on all fuel lines). Changed out line from motor to tank and replaced bulb. Changed out all spark plugs (with NGK DR7EA) and tested compression for them. Also added Sea Foam.

    Took apart carbs and did rebuild replacing the following:
    11-16010-ZV4-005 : GASKET SET
    11-16011-ZV4-005 : VALVE SET, FLOAT
    11-16221-ZW1-000 : GASKET, CARBURETOR
    11-17384-ZW1-000 : GSKT, MUFFLER PLATE
    11-17151-ZW1-000 : GASKET, IN. MANIFOLD
    All other parts were fine and we couldn't see any dirt but did do a full cleaning. Put all back together with specs from manual and still having changing problems.

    We have tested the spark plugs with the motor idling by pulling wire and to see if engine rpms reduces and checking for spark. This is where it has me stumped. At first it was the #1 and #2 carb not reducing the engine rpms. So we tried opening up the air fuel mixture screw (from the standard 2 1/4 turns) and could hear it kick in that cylinder. So we tested the plug for that cylinder and it was firing and then reduced rpms when we pulled the wire. So we thought after replacing all of the fuel things that we would take it out for a drive to see if it might be in the last carb not firing. But after about 5 minutes of driving we noticed a loss of speed so we stopped the boat and opened the cover to now find that the 1 and 4 carbs are not firing and rpms remained the same when we pulled off the plug wire. So we decided to go back to the drawing board. But before we took it back out of the water we decided to check the plugs for rpm loss again and found that 2 and 4 are now not firing but 1 and 3 are.

    Any suggestions would be greatly appreciated. I am about done guessing and coming up empty handed. But on the plus side I do have some extra parts for future use now.


    • #3
      Check spark to each cylinder using a timing light to see if firing on all cylinders all the time.
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