Motor Bogs?

Discussion in 'Bubba's Outboards' started by Clovis, Oct 21, 2006.

  1. Clovis

    Clovis New Member

    Messages:
    165
    State:
    Paris Tennessee
    I have a 17' Lowe with a 70 hp Johnson on it.

    At idle it runs fine.

    Try to give it gas and most of the time it just bogs down. Doesn't die, just sound like you need to down shift.

    Every once in a while it will pick up and go for a bit, then it bogs again.

    My original idea was bad gas, but now I don't think so since I put new gas in it.

    Any ideas?

    Thanks,
    Steve
     
  2. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    It's a fuel-related problem of some sort.

    If it's not bad fuel, then look for a restriction in the fuel lines or an air leak into the fuel lines. If you're using an old metal fuel tank, the pickup may be clogged from rust chunks in the tank -- get a plastic tank instead. Make sure the fuel vent on the tank isn't closed.

    If none of that fixes it, could be a gummed-up carburetor in need of an overhaul. Not a major project if you have a proper service manual.
     

  3. Okccatman

    Okccatman New Member

    Messages:
    323
    State:
    Norman,Ok
    Idles fine but bogs when you give it gas.....hmmm... Have you looked at the throtle advance? It may be fuel or it may be spark(ignition]timing). I know my buddy Had issue with throtle advance and it was similar situation. Good luck. More "educated" help will arive soon.
    Dave
     
  4. Dave L

    Dave L New Member

    Messages:
    1,012
    State:
    Minnesota
    I would first try replacing all the spark plugs, my 25 hp evinrude was doing that same thing this spring until I decided to put in new plugs. It is all better now and cost a whopping $3.14. When I pulled them, they looked like they were the originals and due for new. One appeared wetter than the other which told me it was fouling occasionally.
     
  5. Clovis

    Clovis New Member

    Messages:
    165
    State:
    Paris Tennessee
    Tank is enclosed.

    wouldn't this affect it all the time and not just some of the time?

    And again wouldn't this affect it all the time and not just some of the time?

    I'll check all I can check and I guess we'll see.

    By the way, went back out this evening and it seemed fine on the way out.

    We were just idling back in due to not being able to see in the dark. I need to put some off road lights on the front and plug them into the trolling motor plug.

    Thanks,
    Steve
     
  6. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    You can count on one thing for sure, it's going to get worse. Quit using it until it's fixed.

    Pull the plugs. Put one plug at a time into a plug wire, starting with the top one. Hold the base of the plug to a ground, AWAY FROM THE SPARK PLUG HOLE, and crank the engine. Be sure it's an unpainted metal area you're holding the spark plug to. Look for spark. If you get spark, move to the next plug wire.

    Use a well insulated pliers or a tool designed to hold the plug wire/spark plug to ground.

    If you've got spark on all 3 cyl's, put the plugs back in and run the engine.With the same tool you used to check spark with, pull off one plug wire at a time while the engine's running. Note the reaction in a drop in rpm's when the plug wire's pulled.

    If no reaction, then that cyl's may not be getting enough gas to run. Check all 3 cyl's like that.

    Another check is to run it at a fast idle, not wide open, and push in the key quckly to prime/shoot gas into the intake behind the carbs. Notice what happens. It should bogg down if all is running right. If it picks up rpm's then you've got a fuel related problem.

    You mention bad gas, why? Has it been setting for any length of time? Did you empty the gas tank and then add new gas, or just add gas? Flush the gas lines? Empty the carbs and purge new gas through the lines?

    You can check the condition of the carbs by taking off the cover on the front of the carbs and taking out the bowl plug on each carb. Use a 7/16 wrench to remove these plugs. Catch the gas that drains out in a white paper towel. Look for brown color on the towel and or water and trash. Check the end of these plugs for a sludge deposit.

    Checking your gas can be done by disconnecting your fuel line from the plug in fitting. Quickly and as fast as you can, squeeze the primer bulb to pump gas into a container, prefferably a container you can see through. You'll be looking for water, or trash settling in the bottom.

    I've got a tutorial with pics on here somewhere, showing the rebuild of the carbs on a 70 hp Johnson, I'll try to find it.
     
  7. billcatfish

    billcatfish New Member

    Messages:
    1,571
    State:
    evansville Ind
    i would have to start with the spark plugs if that does not work id try a the gas
     
  8. loanwizard

    loanwizard Well-Known Member

    Messages:
    3,297
    State:
    Coshocton,
    Bob Paul, I don't know if anyone has thanked you in a while, but you are a legend! Thanks for your tireless commitment to the Brotherhood.
     
  9. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Sure I get thanked. Nice of you to mention it.

    Most recently I was thanked for making some of the best BBQ sauce this person ever ate.:big_smile:
     
  10. KansasKatter

    KansasKatter New Member

    Messages:
    807
    State:
    Wichita Kansas
    My 25 hp Mercury was doing the same thing, changed the fuel filter and all was good.