Anyone Know Anything About '60s-'70s 50Hp Merc Outboard?

Discussion in 'The BS Topic' started by danbrennan, Oct 14, 2017.

  1. danbrennan

    danbrennan Veteran Member Lifetime Gold Member

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    Mar 13, 1999
    Brighton, MI
    It will fire very briefly if I manual work the enrichener, but won't stay running. I've been thinking it's most likely something to do with the fuel delivery, but I'm a little puzzled about where the fuel pump is.

    I thought it was the square-ish thing in the first picture, but when I removed it, there didn't seem to be much there. The fuel line then goes into sort of a T, mounted to a cylindrical device, and then the top of the T goes to what I assume is the carburetor(I couldn't get a picture of those, not until I remove the starter).

    I've never worked on an outboard motor before - they don't seem to choke the air? Instead they add more fuel during crank and cold startup? Which is actually what we do with fuel injection on cars, now, of course. I couldn't find anything that looked like a choke.
    MercFuelPump.jpg MercOutboardOnStand.jpg
     
  2. Bandit723

    Bandit723 Veteran Member

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    Oct 1, 2016
    Waupaca WI
    From the looks this might be a pre ethanol? check to see if there is black particles floating around in the fuel system that includes checking the carbs. Also have seen a few of these have the head gaskets leak seen this with folks on the chain of lakes in waupaca.
     
  3. GoldenOne7710

    GoldenOne7710 Veteran Member Lifetime Gold Member

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    Jun 23, 2004
    Athens, GA
    Google search for an exploded diagram of the engine. A lot of the boat parts places will have a diagram with labels and it'll be easy to pinpoint the location of everything you need to know about.

    Last parts I ordered for my boat (sold it) was dusky marine. They had the best prices and every single part I needed when I rebuilt all 6 carbs that were on my '95 Johnson 175hp outboard.
     
  4. 71RS/SS396

    71RS/SS396 Veteran Member

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    Aug 26, 2008
    Wake Forest NC
    Most of the fuel pumps on those older engines were diaphram style, some brands used diaphram style carbs and had no fuel pump. I'm guessing someone still makes rebuild kits for those pumps. The square silver object in the top pic looks like it could be the fuel pump.
     
  5. wiseryder

    wiseryder Veteran Member Lifetime Gold Member

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    Sep 11, 2004
    belding,mi USA
    Yup, that's the pump, you can get kits for them .
    Did you take it apart and inspect it for damage? should be a diaphragm in there
    There pretty simple pump
     
  6. danbrennan

    danbrennan Veteran Member Lifetime Gold Member

    2,763
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    Mar 13, 1999
    Brighton, MI
    My friend and I fiddled all week with this motor, at my Black Lake cabin. The three lower spark plugs looked bad, so I replaced all the spark plugs. We took the fuel screens out(twin carbs, 4 cyl engine), and I took the floats out and checked their adjustment. New Rec 90 fuel, with Seafoam mixed in. We thought we had it when it finally started right up in the garage. But I shut it off quickly, because I didn't have any water going to the water pump. We put it in the lake, but it wouldn't idle for more than 3-4 minutes. Black Lake was really rough anyway, white caps all week, it would have been a rough ride any day last week. Oh well, next year I'll try rebuilding the fuel pump, cleaning the vent on the gas tank, and rebuilding the carbs(yes, there are kits for the fuel pump and carbs). I know a lot more about outboard motors than I did at the beginning of the week, that's for sure.
     
  7. GoldenOne7710

    GoldenOne7710 Veteran Member Lifetime Gold Member

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    Jun 23, 2004
    Athens, GA
    I'd venture to say outboard motors are actually easier to work on vs automobiles...especially these low to the ground 2nd Gen Camaros. They're as basic as any other combustion engine. Air, spark and fuel. Ignition is on a crank trigger. I learned the hard way like you're doing. Boats are almost as addictive as cars once you learn how to wrench on them.
     

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