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Outboard dies at an idle

Discussion in 'Boats and Motors' started by ashtonmj, Oct 13, 2004.

  1. Got a 2001 15 HP Johnson that starts really bogged down consistantly. Alwys have to start it choked no matter how long its been running. Biggest problem lately is it will not idle. You have to instantly close the choke rev it up and leave it idle about halfway. As you can imagine its kinda hard to shift gears and get alot of stop and go manuevering when you cant get close to a slow speed or idle without it just shutting down. I have changed gas hoses like three times thinking it was some problem with fuel pressure or air. Something similar happens with a 8 hp yahama that has to rich of a gas mix to it. Suggestions ...? bad gas? clogged fuel line/filter? This is driving me nuts, and it can be dangerous because I work on this boat and many times on rivers in industrial areas. It has been unsuccessfully and VERY unsatisfactory serviced at a for now annoymous akron area boat dealer. I need help!
  2. Is it a 4 stroke or 2 stroke? The first thing I'd check is if it reacts if you pump the bulb. If so, the fuel pump should be rebuilt. If not, I'd suspect the carb(s) need cleaned, if a 2 stroke. There's plent of other possibilities, but those are the most common.

  3. Suggest you consider speaking to Brudges Marine. He is a Johnson expert and has done good work for me in the past. See if he has any idea of what it could be and decide if you trust his approach.
    Befor you contact Bridges, take it back to the other guy and see if he will pursue further action at no charge.
  4. It is a two stroke and I doubt it was regularly serviced in its life time. It was given to us by a fellow contractor who happen to drop one of our motors off the boat into a remediation site. I have tried pumping the bulb before in the past a couple times and that did not seem to do much help but I am going to give it another shot. Part of the reason why I used two different diameter hoses too thinking it might be something with the pressure. And for the price I payed for 2 silly parts on the pull start you bet they will be fixing it the right way this time. Where is brudges marine?

    Thanks for the input so far
  5. Sorry, but I mispelled it. He is in Akron on Cuyahoga Falls ave. 330-929-2311.
  6. I Second What Shortdrift Said..bridges Is An Expert On Johnsons
  7. UFM82

    UFM82 The one others want to be

    It sounds like the idle jet is clogged- it'll run on the choke because you are sucking in fuel when you close off the venturi. When you open it up, you lose the fuel flow. The easiest way to attempt a fix is to unscrew the idle screw and take it out. Use a can of carb cleaner with the straw/tube on it. Stick the tube in the hole where the screw came out and blast it. Maybe it will dislodge/dissolve whatever is in there blocking the passage. Count the turns as you remove the screw so you can put it back in in the same place. Try the motor after that. If it isn't any better, you'll need to pull the carb and clean out the bowl and the jets. A kit might cost you $20. It's actually a fairly simple job.

    Try that before sinking a couple hundred with the shop.

  8. freyedknot

    freyedknot useless poster

    how bout the vent on the gas tank??? is it free and clear of debris?
  9. I'm with UFM on this one,dirty carb.It is starving for fuel having to choke it.
  10. silly question...but where is the idle screw at. I want a little better idea before I unscrew something that I suspect is it. What about giving some compressed air a shot into the carb as well? Going to give it a bit leaner mixture too it seemed to be running really rich and I've seen a few posts elsewhere that this is often a culprit.
  11. the carb is as clean as a whistle....
  12. I think you should buy a manual for your motor. It's well worth the money and has step by step instructions on many procedures. Does the carb LOOK clean, or do you KNOW it's clean. It takes very little to make a motor run just like you describe. It's starving for fuel, and if it's not the line or fuel pump, it's probably the carb. The only way to truely clean the carb is to disassemble, soak all metal parts in cleaner, and blow out passages with compressed air. I'm fairly confident that's your problem. It's also an easy fix, so I'd at least try that first. They need done from time to time anyway.
  13. Marshall

    Marshall Catch Photo And Release

    i had a simialr problem with my johnson 50. It would run at full speed fine but when i would idle it would stall. It would not sit and idle without having the throttle forward. I really never had to use the choke after i got it running though. I was told by a mechanic to ajdust the carb screws a little because it may have been running too rich. I figured if i mess it up i would have had to pay to have someone fix it anyway so i tried it. I put a mark on both screws before i made any adjustments so i could put it back to where it was. My owners manual showed me which way to turn the screw to make it run less rich or more rich. In my case i was running too rich. I moved the screw from around 11 oclock to 1 oclock on both carbs and man what a diference. It purrs like a kitten and has all summer since i made the adjustment. In the manual it says if you turn the screw to far it will run badly and maybe backfire. Im sure you dont want to overadjust it but turn it just enough to let it idle smooth. Worked for me and saved me 75 dollars an hour labor costs. I did all this in about a half hour. I have a drum i filled with water and ran it in my driveway. Im no expert here but my motor has run better now than when it was brand new. Just a suggestion good luck.
  14. UFM82

    UFM82 The one others want to be

    I'll take that to mean you have already removed it and disassembled it. If not, the outside appearance of the carb has nothing to do with the inside.

    On that size engine, it should be a relatively simple thing the remove the carb. Other than linkage and maybe an air horn or something it should be easily accessible. Once the carb is off, remove the one screw that holds the fuel bowl on. I'll bet there is dirt laying in the bottom. ( There almost always is.) Take the float and needle off and lay it aside, being careful not to damage it. You will see a screw with a spring on the shaft on the body of the carb- that will be your idle screw. Take that out, counting the turns as you do so. That will open up the passageways of the carb. Take a can of carb cleaner with the straw attached and blast it through the passages you find. Hit them all and watch out for backspray. Some of those holes may point back towards your face and carb cleaner doesn't feel real good in your eyes. :eek:

    Once you have that part done, make sure you have new gaskets to reassemble everything with. Put the float and needle back in place and carefully reinstall the fuel bowl. Once the bowl is on, you won;t have to worry too much about how you hold the carb- the float can't come off the pin that holds it on. ( You may cuss that pin during reassembly. LOL)

    Put the idle screw back in the number of turns you counted taking it out. If you have forgotten how many turns, screw it in until it bottoms and then turn it out 1 3/4 to 2 turns. That will be close enough to get started.

    Hook everything up and try to run it. If you have been successful, it should start up and run OK. Then, after it warms a bit, you can adjust that screw until your idle is good. Too rich and it will stumble- too lean and it may pop back through the carb.

    A manual will be a big help if you don't already have one.

  15. sounds like the idle jet, also know as the pilot jet needs to be cleaned out.
  16. My 1983 Merc 9.8 had almost identical symptoms. He told me it was build-up on the exhaust ports. Runs like a new one. No new parts, just cleaned the ports.