motor problems. need help again. thanks.

  • neilyo
    Posts: 27
    August 5, 2011 at 3:42 am #1238592

    i have a 1978 mercury 115 that runs for 15 min then will not start again. runs like a top then bam day over. coil???? any tips would be great. miss fishing so bad.

    joshbjork
    Center of Iowa
    Posts: 727
    August 5, 2011 at 4:06 am #986388

    Sounds like that or a plugged vent.

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    August 5, 2011 at 10:48 am #986392

    What Josh said.

    Once it doesn’t start can you smell gas? If you can it’s likely not a vent issue. Also, is the fuel bulb hard or soft after it quits.

    Once it doesn’t start pull a plug, lay it on the engine with the spark plug cap on and have someone turn it over.
    If there’s no spark, it’s an electric issue.

    I’m not an engine guru, but that’s a good place to start.

    neilyo
    Posts: 27
    August 5, 2011 at 1:10 pm #986428

    thanks for the tips guys. i have blown out the vent. also tried running it with the gas cap off. i haven’t tried pulling a plug and seeing if it has spark out there as i am usually alone. a fiend of mine says its the coil. then i read it might be the switchbox(super expensive) i put a new coil in still had the 1978 original in it.
    trying it tomorrow morning. hope it works.

    kroger3
    blaine mn
    Posts: 1116
    August 5, 2011 at 2:29 pm #986453

    sounds electrical, with heat builds resistance usually causing and open short in something. cools down and goes back to normal.

    john23
    St. Paul, MN
    Posts: 2578
    August 5, 2011 at 2:44 pm #986458

    Sounds like it could be a fuel supply issue. How long do you have to wait before you can run it again?

    I’d check the fuel filter in the engine first. If that doesn’t fix it, check to make sure there isn’t anything else between the fuel connection and the carb that could be obstructing the fuel flow (it could even be the connection itself, but not likely the male side). If the fuel line looks good inside the motor, try a different gas tank to see if the problem is in the engine or in the tank.

    I had a bad coil on a 1986 Evinrude 70 that had three cylinders. One coil for each cylinder meant that the bad coil didn’t kill the engine, just one of the three cylinders. The engine didn’t die, it would just run very poorly. When coils go bad they can work fine when you start the motor, but fail after they heat up.

    Take that info for what it’s worth. Good luck!

    joshbjork
    Center of Iowa
    Posts: 727
    August 6, 2011 at 2:57 pm #986628

    Hey, if the fuel pump is bad, you run for a few minutes after you prime the bulb and then run out of gas also. Although running out of gas there is a lot of sputtering.

    Jaya
    Zimmerman, MN
    Posts: 174
    August 10, 2011 at 9:41 pm #987613

    sounds stupid but is the water pump working? I know a guy that had the same problem, thought it was electrical so he brought it in and it turned out to be a cooling issue, they replaced the pump and it fixed the problem. It was an 85 johnson 25

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