2 dead 2 stroke 30 Mercury's

Discussion in 'Outboards' started by DriesLaas, Nov 4, 2019.

  1. DriesLaas
    Joined: Aug 2009
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    Location: South Africa

    DriesLaas Weekend Warrior

    Both the 30/40 hp 2 stroke 1995 Mercury's on my boat died within seconds of each other, and have remained so.
    The motors were starting easily every time during testing on land. I bought this old boat and this was the first time I took it to sea.
    Both carbs are clean, fuel supply lines are brand new and airtight, and there is good spark on all 4 (2 per outboard) sparkplug.
    I mixed oil in with the fuel and drained the oil tanks. No oil level alarm ever came on. Desperate here, the Dorado are starting to bite and I am baffled. Any ideas?
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Apologies, I am a bit slow on the uptake, and I don't really understand your post.
    When you tested the engines on land, was this using a portable fuel tank - ie a different fuel tank to the one used on the boat?
    Maybe the petrol in the tank on the boat is old and crappy?
    You mentioned that you 'drained the oil tanks' - I am baffled here. Did you turn off the separate (2 stroke) oil tanks and feed an oil / fuel mixture directly to the engines? Or did you drain the fuel tanks?
    Do you have oil level alarms in the oil tanks (if fitted)?
     
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Yes, it is a little confusing.

    If you are now premixing, did you block off the old oil feed lines?

    If both motors stopped within minutes of each other, and you still have spark, then I’d be looking at the fuel tank. I’m thinking they both may be running off one tank that has water or gunk in it.

    If separate tanks were used, check to make sure the vents are open.
     
  4. DriesLaas
    Joined: Aug 2009
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    DriesLaas Weekend Warrior

    I apologize for not describing properly. The two fuel tanks were filled with fresh fuel, and oil added 50:1 ratio. Breathers were definitely open.
    The oil tanks are the autolube oil tank on each motor. I simply drained them. No other measures taken like blocking off the supply tube, or isolating the oil pump. No low oil level alarm was given by either motor, which I would have expected.
    I added some oil to each tank afterwards to clear any low oil level condition, no joy. I am not sure whether the motor does anything more than sounding a buzzer when the oil level goes low. Wiring diagram shows the oil level and temp sensors going into the control box, not clear how the logic works from there. I need to add that both motors were running initially, with the stbd motor rpm hunting. I thought that cavitation maybe caused the hunting rpm. I stopped both motors, tilted them fully upwards to adjust the position of the trim manually, and then neither motor would start.
    Back on land, I replaced the sparkplug with new ones, and tested the spark. I did not check the actual ignition timing, it seemed regularly timed during the spark test, and what are the chances of both losing timing at the same time. I also cleaned the carb of stbd motor, could see nothing in the fuel that caused concern. I also drained the carbs, and checked fuel supply up by squeezing the bulb with the drain plug removed. Immediate and clear fuel supply to the carb is verified.
     
  5. baeckmo
    Joined: Jun 2009
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    baeckmo Hydrodynamics

    Check the fuel. Where did it come from, did you fill both tanks at the same time-same place, was it the "bottom residue" from somewhere, full of water? Is it really gasoline?
     
  6. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Might have something to do with your getting rid of the auto-mix, perhaps air is being sucked into the fuel line.
    " No other measures taken like blocking off the supply tube, or isolating the oil pump. "
     
  7. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    If you don’t block off the oil injection pumps they will pump air into the fuel lines.

    I don’t know if your motors have a shut off for no oil flow, but not hearing the alarm may just mean it doesn’t work or has been disconnected.

    The timing won’t change, and the odds of the timing changing on both motors at the same time astronomical.

    These oil injection systems are very reliable, more reliable than the owner remembering to add oil.

    Messing with motors when you don’t understand how all the components work together can be very expensive.

    I’m not saying they’re damaged, it may be something simple, but you need to get a better understanding of how everything works before you start doing any more modifications.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Tinkering has its perils
     
  9. DriesLaas
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    DriesLaas Weekend Warrior

    My thinking currently is to take the air filters off, flood the carb with ether (Easystart, Pilotstart, something like that) and start. That will at least indicate that air-fuel mixture is flowing into the crankcase and then into the combustion chamber, compression occurs, and ignition happens at the right time. If this works, the carburator function of creating emulsified air-fuel mix and metering it to the powerhead is the only thing that can still be wrong, and it might be as simple as cleaning carbs again.
    Is there a way of checking that emulsification of fuel happens correctly, as a functional test? A friend briefly described drawing air though the carb with a vacuum cleaner to see if it functioned properly???
     
  10. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    This is getting a bit crazy.

    There is absolutely no need to check a carb with some contraption built from a vacuum cleaner, which would be a bomb if you actually used gas in the carb.

    You said the carbs were clean, but being clean yesterday doesn’t mean they are clean today.

    Using some starting fluid will let you know in about two seconds what area to look at. Starting fluid isn’t good for a motor so just briefly check it. Also, get some designed for a two stroke, it will have oil in it.
     
  11. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Ether is never used in the manner described.

    A tiny small amount of ether is only used or you will bend crankrods or the crank.

    If you have spark, then try to see if you can choke the engines. If you choke them and see fuel; they are getting some fuel. But rpm hunting is indicative of inconsistent fuel supply.

    I added "some" oil to the tanks is also concerning. The oil tanks should be filled.

    So, guessing you are just not accurately cleaning the carbs.

    If you don't soak them in carb cleaner; don't mess with ether.

    why anyone would switch from oil injection to mixed oil is very perplexing; you would at a minimum be introducing an overrich mixture at the beginning which would probably clog carbs and badly carbon the cylinders
     
  12. fallguy
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    fallguy Senior Member

    Also, the engines probably carboned. The only way to fix if you can is running them wide open if you can get them to fire.
     
  13. baeckmo
    Joined: Jun 2009
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    baeckmo Hydrodynamics

    Yup, crazy and dangerous! Please DriesLaas, think (and listen to ondarvr...) before doing anything that you can't control! There must be a logic in trouble-shooting; what was the last thing you did to both engines before the trouble emerged? That is where you should start thinking.

    As far as I understand it, you attached newly filled fuel tanks with premixed oil and drained the oil reservoirs......correct? The Merc two-stroke lubrication requires some extra thought, google "mercury 2stroke oil injection" or see the owners manual for correct procedures for getting rid of air in the oil system. Some of these systems operate with pressurized oil tanks; that means the tank caps must be tight. Get these things sorted out first!
     
  14. DriesLaas
    Joined: Aug 2009
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    DriesLaas Weekend Warrior

    Gents, as always, thanks for the thoughtful responses.
    My carb testing friend also regularly cuts old fuel drums in half with his cutting torch, and smokes at the LPG refilling station.....
    Luckily he is emigrating to Australia soon!
    No seriously, we do try to not be complete rednecks, even though the urge undeniably exists, and I have used the phrase: "Hold my beer and bring the angle-grinder."
    The use of the term "flood carb with ether" was just poor use of language on my side, I have used it in the past and I followed the directions on the tin. Something like :"spray for two seconds directly into carb with air filter removed...?"

    I will try to be more methodical about trouble-shooting. Here is the new proposal:
    • Clean the carbs properly with carb cleaner
    • Check absolutely no debris of any sort in fuel tanks
    • Fill oil tank on motor
    • Prime oil delivery system so no air is in system
    • Choke carb and see if fuel is delivered
    • Test with ether in prescribed manner
    If all of this does not work, I will get vacuum cleaner guy to ballistically present burning match to open fuel tank and run. Video footage will be available on Youtube, press like and subscribe.....;-)
     

  15. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Gasoline is explosive enough to be pouring down your carburetor.
    Only tiny amounts are needed to turn over a healthy engine.
    No ether, no carb cleaner, just small amount of gas.
    But be careful!
     
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