Conference vicki::boats

    
    
    	i think youll find the omc tank has a vent but its built 
    into the cap otherwise the tank would collapse.
    
    wet plugs could also be mixture/float  level choke stuck or as you said 
    pressure. 
    
    id try the standard heat range plugs again and check my mixtures
    etc. 
    
    im assuming this is an o/board 
    i find if i tilt my motor up overnight ill have the carbys
    drain into the well.
    
    the other 
    reg
    
    
    

    Wow, that was quick! Thanks!
    
    Well, to put it another way, there doesn't appear to be a vent, as the
    Tempo tank has a knurled brass screw with one side of the threaded
    shaft ground down which seats on a rubber gasket in the center of the
    filler cap. The OMC has what looks like a dime sized rivet in the cap. 
    It's in there tight.
    
    Moreover, by either loosening the cap on the OMC tank or raising the
    screw on the Tempo, the gas in the water problem goes away. Leaving the
    OMC cap on tightly while docked = gas in the water. 
    
    Under what circumstances should I open the tank vent? I had assumed
    that the OMC tank had no vent, so I've been running with the Tempo vent
    closed.
    
    Has anyone ever experienced a similar trolling speed stalling problem?
    The motor seems to run fine at high speed, and runs well when dropped
    to idle, but then slowly loses RPMs then stalls. OH OH, this is
    starting to sound like fuel starvation, maybe I answered the vent
    question myself?

    
    
    	i reckon you might be right 
    
    the omc tank as i recolect has a one way vent 'it will allow air in
    but wont allow pressure out until it gets really high, the other 
    tank should have the vent open whilst running,and for your problem 
    id disconnect the fuel line whilst it is sitting unused.
    assuming an outboard.
    if you havent opened the vent you will lean out and stop as 
    you have described also the tank will bow in at the top or sides
    until you do stop and it can drag air back along the fuel line this 
    may explain why you have trouble starting after stalling as the 
    lines are full of air.
    lean running in a two stroke is not good 
    by the way. although you will have increased performance for 
    a while then "boom".
    
    the other reg
     
    

    Well, now we're getting somewhere! (And at this hour...)
    
    I'm going to change the plugs and try idling it around for a while.
    
    I'll let you know how I make out.
    
    By the way, it's a 1989 Evinrude 70 with VRO and power t&t.
    
    Thanks Reg! (other)

    P.S.
    
    Do you think I might have damaged my engine? I stalled it three times,
    and ran it for maybe one hour on the Tempo tank with the vent closed.
    

    
    
    probably no real damage yet but its something to be aware of
    the plugs are generaly a light brown colour if its the right mixture.
    
    hope it runs well 
    
    the other reg
    
    
    

    When running the vents should be open, otherwise, obviously the engine
    fuel pump will pull a vacuum on the tank and the engine will run out
    of available fuel.  Generally one would keep the vents closed when
    the boat is moored/docked, but you seem to have the pressure build up
    problem blowing gas into the water.  I would keep the vents slightly
    cracked open when the boat is not running.  The vents can be closed
    for transportation of the tanks (in a car for example) or for long
    periods of cool (out of sun) storage.
    
    Why not replace the plugs and see how the engine is doing now that 
    you have the vent problem under control?
    
    I assume your system uses the rubber squeeze bulbs in the fuel line
    for priming?  If so, you can tell if your properly vented by observing
    the priming bulb while running the engine.  If the bulb collapses
    in then you know you are pulling a partial vacuum on the tank, and
    it is not venting properly.
    
    Jeff

    
    	Many moons ago ... I went through this and now of course
    	I lost my brain (and my outboard) and can't remember reality ... 
    	so I'll wing it.
    
    	I had the fuel in the water prob with my old Johnson outboard.
    	I disconnected the fuel line when I was done for the day.  No
    	big deal, especially since I had a couple of lines, depending 
    	on if I was using the 6 gallon tanks or the inboard tank.  Besides,
    	I think most engine manufacturers "recommend" disconnecting the
    	fuel line from an outboard when not in use.  
    
    	I seem to remember some engines require tanks that are made to vent, 
    	others aren't ... which I expect means a controlled vent vs 
    	uncontrolled venting, since you do need some way to displace removed 
    	fuel with air.
    
    	Do you have an owners manual for the outboard ?  It might mention
    	the tank requirements (besides recommending an OMC tank ;-)   )
    	ie: venting .
    

	I'll hazzard a couple of guesses, since I have very little experience
of outboards they'll be based on what the base noter wrote, some carb knowledge
and  "GUESSWORK" (-:

	I think the gas in the water is an indication that the tank isn't
properly vented (already said) or....  the stalling problem might be related.
Someone already said that the stalling might be due to a float or fuel level
problem, my guess is that your float isn't cutting off the gas to the carb.

OK, its a guess and I admit that I really don't know how much pressure it would
take to push a float valve needle off its seat and flood lots of gas into the
lake, neither do I know how much pressure would build in a 6 gallon tank on a 
hot day.  I believe that a vent or pressure relief of some sort should open 
before the carb floods and pressure won't build in a tank as fast as the
gas is consumed, so you have a carb or engine problem anyway.  If you fix that
the vent question may become a non-issue.   

	Come in Rick Wilson.

We went through this exercise with my father's boat last year, so I think 
I understand how it works.

Original equipment OMC tanks have a non-vented cap.  The tank is vented via
a spring loaded pin on the fuel connector.  When you attach the two halves 
of the connector, the pin is pushed in, and the tank becomes vented.  With
the line disconnected, the tank is non-vented, and can build up very large
amounts of pressure if left in the sun.

Some aftermarket tanks do not use the vented fuel fitting, they use a vented
cap instead.  If you use the correct (vented) cap with your Tempo tank you
should have no pressure buildup problems.

Excess pressure buildup can be caused by at least two problems;
1) A stuck or broken vent pin on an OMC tank
2) Using a non-vented OMC gas cap on a non-vented aftermarket tank.

Since you mentioned that you had to attach an aftermarket fuel fitting to your
tank, I'd be willing to bet your problem is #2 above.  On my father's tank, the
vent pin was busted, so we switched to a vented cap just for that tank only.

Also, you should check your carbs and fuel lines for leaks. Unless the pressure
buildup is astronomical, your fuel system should be able to contain the excess
pressure without venting it into the lake.

Rick

    
    
    My Yumamama is the same way. non-vented cap. The connectors on both
    
    ends of the fuel line have a pin and a and a spring loaded ball.
    
    i.e. the tank is vented by the line, no the tank.
    
    My OEM tank is in pretty bad shape, the handle and hose holders
    
    metal parts are all but falling off.    There's a limit to what 
    
    you can do with a metal tank especially when it lives in the salt
    
    all season. I just bought a Tempo aftermarket plastic tank.
    
    The tanks come without fittings, you buy the one for your engine
    
    hose and install it on the tank. The cap has a vent, since the original
    
    tank was vented by the hose, my guess is i should keep it closed????
    
    
    Calling Dr. Wilson, Dr. Fein
    
    
    JIm

      Thanks Rick, you saved me some typing. I would just like to add that
    there are TWO spring loaded pins in an OMC tank fitting. One is the
    vent and the other is the fuel. Attaching the fuel hose opens the vent
    and also opens the fuel (valve). I would like to also add that you may
    simply have a loose or worn or otherwise bad float valve in one carb,
    but to have all three be bad in that way at the same time is like
    winning the lottery - it can happen, but the odds are pretty high
    against it. So check the valves, the o-rings in your hose and all fuel
    connections.
    
    					Kenny

    Oh yeah, to answer your other question - if you're using a vented
    cap and a non-vented aftermarket fuel fitting, you should defintitely
    leave the cap vent in the OPEN position.  Otherwise, you'll create
    a vacuum in the tank.  This would explain why your motor dies while
    trolling, at idle speed the fuel pump creates very little suction
    and cannot overcome the vacuum in the tank.
    
    When leaving the boat unattended, the cap vent should be left CLOSED.
    Otherwise, any expansion will be vented all over the floor of your
    boat.  As mentioned earlier, your fuel system should be able to contain
    this pressure.  If it leaks, you may have nothing more than a simple 
    fuel leak or bad carb needle valve.
    
    And of course using a non-vented aftermarket fuel fitting in conjunction
    with a non-vented cap (or leaving a vented cap closed) is going to cause 
    you problems under any circumstances.  You've gotta be vented somewhere
    while the engine is running, either at the fuel fitting or at the cap.
    
    Rick

    I assume that this means that using an original OMC 6 gal tank with
    the two position metal lid that one DOES NOT have to move the cap to
    the vent position..... one can leave the tank sealed since the vented
    fuel connector will take care of it... is this correct?  I have the
    non pressure type tank with the single line fuel hose with the
    squeeze bulb in the hose.  A few weeks ago I did not open the vent
    on the OMC metal tank and the engine sucked the rubber squeeze bulb
    flat and the engine stopped... so I assume that my system does not
    have the vented fittings.  The fuel hose fittings are OMC after market
    replacements.  
    
    Jeff

    
     Jeff,
    
       It's hard to say from your description. But ever since OMC went from
    double hose 'pressurized' tanks to single hose, they have used the
    fittings I described in their METAL tanks. Now I know they've since
    come out with some plastic tanks, but I do not know what kind of
    venting they use in those. If you remove the hose from the matal tank,
    you can easily see the two spring-loaded pins which provide for tank
    venting and fuel shutoff for when the hose is removed. If your squeeze
    bulb got sucked in but the motor kept running, be sure that it is
    installed with the 'flow' arrow pointed towards the motor.
    
    	And yes, with the OMC metal tanks, you should always leave the fuel
    cap on tightly. I believe it has two positions so you can release the
    pressure from the tank without having the cap come flying off at you.
    (pressure caused by the tank getting warm from being in the sun etc.
    Note that the tank should never get pressurized if you have a hose
    connected to it, since the integral vent is open whenever you have a
    hose connected - this is only for the tanks with removable hoses! - for
    all I know OMC has some tanks with non-removable hoses now.)
    
    					Kenny

    I assume (there I go assuming again) that the aftermarket OMC fuel
    connectors are vented too... after all if they are a direct OMC
    replacement then they "must be" the same.
    
    

    Jeff,
    Wrong assumption.  The aftermarket (Tempo) OMC connectors are not
    vented.  That's why the Tempo tanks have a vented cap.  As far as
    I know, only the original equipment OMC metal tanks have vented
    connectors.  As Kenny said, look for the two spring loaded pins 
    sticking out of the male connector (tank side).  If they're not
    there, your connector is not vented and you NEED a vented cap.
    
    Rick

    
      That's right. The OMC 'aftermarket' stuff does not have the
    'automatic' venting via the pins because they have to be able to just
    screw into a threaded fitting. In the OMC metal tanks, it is an actual
    assembly - not just a replacable fitting.
    
    					Kenny
    
      NOW, lets find out why this motor runs poorly!

    Just to let you all know, my problemis solved. This conference is
    great!
    
    Thanks for all the help!