Outboard Marine Motor bogs down when giving it throttle

Discussion in 'Bubba's Outboards' started by LittleRiverBigFish, Oct 2, 2007.

  1. LittleRiverBigFish

    LittleRiverBigFish New Member

    Messages:
    35
    State:
    Iowa
    Bubba,

    If the plugs are wet and oily, what is the next plan of action?

    Last time I had my boat out, it was very reluctant to start (usually starts on 1-2 pulls). When I did get it started, it too would bog down when I gave it gas. If I let off the throttle it would come back to life and then run fine if I accelerated gradually. After reading this thread, I pulled the plugs last night and both were oily and wet.

    A friend of mine suggested that since my fuel line had been connected for a day or two outside that the expanding gases in the tank could have possibly forced fuel into the motor, essentially flooding it out. Thus the reason it was hard to start.

    Any thoughts? Is it time for new plugs?

    BTW, motor is an '88 Johnson 30 hp.

    That was my line of questions from the previous thread, now I have some more and responses to the questions some of you asked. For background, I bought this motor used a month ago. Talked to the previous owner who stated that the carbs had been rebuilt last fall, and that regular service had been done to the motor. It ran fantastic for the first couple of trips I took- started on first or second pull, idled smooth, had great power etc. The previously stated problems arose the last time I had it out. The motor came with a tank of gas that had stabilizer in it, but I'm not sure what brand nor do I know how old the gas was. It also came with the original fuel line (rubber) and fuel tank (metal). I'm beginning to think it may be the old(?) gas and or sediment from the metal tank or the old fuel line. However, from a visual standpoint, both the tank and the fuel line appear to be in good shape.

    Now that said, how do I do a spark test? Compression test I have seen on here before but don't have the vacuum pump to do it. I may start with the Seafoam treatment that has been described on here many times to see if that clears things up. Duck season is coming soon and I would really like to have this problem resolved. Thanks for the help!
     
  2. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Look at the fuel pump and there should be a big screw right in the middle of it. Take that screw out gently and remove the cap and see if there is any derbish clogged up in it.
    This is why I recommend adding a fuel water seperator on any motor. It will save you a lot of trouble and best 25 bucks you will spend.
    Those plugs looking the same tells me that the head gasket is still most likely good. no water getting to the spark plug.
    You can test the spark to see if all plugs are fire ing by taking a blade screw driver and putting it in the plug wire that hooks to the plug and hold it about 1/2 inch from a good ground on the block and turning the motor over. A good spark or a good shock lets you know that the coil is fireing.:big_smile:
    You will need a tester to do the compression test.
    Smell that fuel and if it don't smell right get rid of it and if that tank has the least bit of rust in it get rid of it and those lines will start coming apart from the inside not where you can see it,
     

  3. Eurolarva

    Eurolarva New Member

    Messages:
    21
    State:
    Minnesota
    If by chance you ran this motor without opening the vent screw on the gas can you could have ruptured the diaphragm on the fuel pump. I am not familiar with this particular engine but from the description of the problems you are having this sounds like a fuel pump problem. When you pump the primer bulb does it get hard?
     
  4. LittleRiverBigFish

    LittleRiverBigFish New Member

    Messages:
    35
    State:
    Iowa
    Willard, thanks for the spark test info. I've actually seen someone do that (the shock part). There was an old salt at our duck camp who was a genious when it came to fixing the old Johnson/Evinrude Ducktwin motors, if you had problems you took it to him. The "spark test" was one of his favorite tricks for the unknowing. Never ceases to be funny to see a grown man hop around like that!

    Eurolarva- yes, the primer ball gets hard. In fact, the day I had trouble starting the motor, it was hard (pressurized) from the get go. I wondered if the motor was actually getting gas. This is my first experience with metal tanks and I think I will switch back to my plastic one.
     
  5. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    Ditch the old metal fuel can,dump the fuel line and install a new one.You are most likely getting air in the system.Hard to detect this and when you inspect the fuel line you might not see it or the valve in the bulb can be passing air also.NEVER in my humble opinion,try and run a motor with fuel from a can or container that you didnt purchase and treat yourself.You dont know how old the fuel is or WHEN it was stabilized.:smile2:
     
  6. LittleRiverBigFish

    LittleRiverBigFish New Member

    Messages:
    35
    State:
    Iowa
    One odd detail that maybe I should have mentioned, based on some of your comments. When I had the boat out last, I kept hearing the sound of air filling or being expelled from a metal tank. My fire extinguisher, which is old, sits next to the fuel tank. I thought maybe the sound was coming from it. Could it have been air getting into the fuel system as you've mentioned?
     
  7. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Or it was trying to get enough air into the system to run. Take the lid off and try it or change tanks with some fresh fuel.
     
  8. Eurolarva

    Eurolarva New Member

    Messages:
    21
    State:
    Minnesota
    I agree with bubba. try running without the cap. Your motor maybe struggling to vent. I prefer plastic over metal. Easier to clean, no rust
     
  9. LittleRiverBigFish

    LittleRiverBigFish New Member

    Messages:
    35
    State:
    Iowa
    Thanks to all for your help! I'll be switching tanks and fuel lines this weekend, mix some new gas and be on the water Monday.

    Will report back with results...:roll_eyes: