Yamaha 25 hp fuel problem

Discussion in 'Boats and Boating' started by Hank49, Aug 2, 2008.

  1. Hank49

    Hank49 Scuba Instructor

    # of Dives:
    Location: Mullins River, Stann Creek, Belize
    6,174
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    I have a 2005, 25 hp that hasn't been used for about two years. When I started it, it runs but I need to keep the choke on about halfway, or it stalls. If I keep it partially choked, it runs fine.
    This tells me that perhaps it's got an air leak somewhere else? There is no gasket where the carb attached to the block, which seems strange. I put new plugs in and new gas, flushed all the lines. One thing I notice is that the fuel filter housing is not full of gas while it's running.
    Anyway, I live in the middle of nowhere so I'm hoping maybe one if the SB experts could come up with a simple explanation. :D
    Pescador? Where are you, amigo?
     
  2. Spd 135

    Spd 135 Manta Ray

    # of Dives: 500 - 999
    Location: Slidell La
    713
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    clean your carb and the bowl really good. They tend to laquer up. My 70 yamaha had a similar issue when I bought it.
     
  3. Nemrod

    Nemrod Giant Squid

    # of Dives:
    Location: Dixie/High Plains
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    Does the fuel taank have a vent?

    Does the engine run if you pump the bulb?

    Is there fuel in the carb float bowl?

    Is the fuel line to the engine clear?

    N
     
  4. Hank49

    Hank49 Scuba Instructor

    # of Dives:
    Location: Mullins River, Stann Creek, Belize
    6,174
    958
    113
    Hi Nemrod,
    1.Yes and it's open
    2.No, it still stalls. It will run fine,( smooth, high rpms, no stalling), if I pull the choke knob to about 1/3 or so out.
    3.Yes, a lot of gas came out when I took out the drain plug screw.
    4.Yes, I disconnected the fuel line into the engine, depressed the check valve and really flushed it hard for about 5 pumps on the bulb.

    I did notice that the fuel filter housing is not full of gas though.

    Spd 135, I'll give that a try. I've been hesitant to tear it apart. I'm afraid it might end up in the pile of fishing reels that I've tried to fix. I'm really good at taking stuff apart....putting it back together is a different story. Thanks, gentlemen
     
  5. Nemrod

    Nemrod Giant Squid

    # of Dives:
    Location: Dixie/High Plains
    11,109
    1,373
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    I think you need to pull the bottom of the carb off nad inspect the main jet that it is clear. Usually these screw into the bottom of the carb and have the slide needle through them. In other words, clean the main jet and flsuh the passage.

    There is often a "last chance" screen in some carbs, find it and make sure it is clean.

    With all of the weird fuel around today, make sure none of the fuel lines have collapsed or swelled up or are shedding material internally.

    Make sure the carb float has not become the HMS Titanic and no longer floats. These sometimes fuel log or cease floating for various reasons, make sure as well the float is free to move over it's full range. Is the float needle free and clean?

    N
     
  6. Chuck Tribolet

    Chuck Tribolet Loggerhead Turtle

    # of Dives:
    Location: Morgan Hill, CA USA
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    If it were a sunk float, half choke would make it run worse, not better.

    Since pumping the bulb didn't make it better, it's likely not a problem with fuel not getting to the
    carb, but "fuel filter housing not full of gas" is a contraindication.

    Since the half choke makes it better, the problem is that it's running too lean. Could be too much
    air (a leak), could be not enough gas.

    "hasn't been used for about two years" makes me think gunk in the carb. But no gas in the
    fuel filter housing is also significant.

    Is this a two-stroke or four-stroke?
     
  7. Bigdaddy29111

    Bigdaddy29111 Garibaldi

    4
    0
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    I had the same problem on a 50 yammie I bought a while back. Get a bottle of seafoam
    ,mix it by the directions, go run the p*ss out of it. You'll think you have a different motor.
     

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