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  1. #1
    Seaman Apprentice
    Join Date
    Jul 2009

    Default Yamaha 90tlr - How to drain the carbs - the correct way.

    Its a 2008 two stroke. with 40 hours. Had the 20 hours service. Of course, I run the corn laced gas. I probably wont use the boat for a month or so since its January and getting freakin cold. Ok it's Charleston SC but its cold to me.

    Rodbolt says - you are not going to drain all of the gas out of the carbs by pulling the fuel line and lettin her run out. This was from another post. With that said -

    Is it reccommended to drain the carbs if the boat will sit for 30 to 60 days?

    The next question is probably answered in the engine manual of which I don't have...yet. I ordered the yamaha one.

    What, if any, loctite type stuff should be put on the drain screws when replacing? Is there a torque spec or just nice and snug?

    Rodbolt - thanks for all of your great information you give the members of iboats. You tell it like it is and the way it should be done or else..."poof goes your engine" Also, I didn't realize you were a Yamaha Master Tech however I should have. Your knowledge of Yamahas is increadable. Considering the amount of time you must spend on this site tells me you don't need to look at the manuals very much, you already know it. I was also surprised there are only about 50 in the states. You are a member of a very exclusive club there. Congrats.

  2. #2
    Rear Admiral
    Join Date
    Apr 2009

    Smile Re: Yamaha 90tlr - How to drain the carbs - the correct way.

    Brass 10MM hex screw/drain plug on bottom/side of each carb, just remove each one, drain onto a clean white rag to see what was in carb and to catch drain plug if you drop it, with plugs out pump primer bulb to flush out float chamber, replace plug snug, easy and quick job on the 90HP, probably a good idea to drain carbs whenever motor not run for a few weeks, use Stabil Marine, Ringfree all the time, install fuel/water separator, eliminate most fuel related problems. Good Luck!

  3. #3
    Supreme Mariner
    Join Date
    Sep 2003
    Kitty Hawk NC

    Default Re: Yamaha 90tlr - How to drain the carbs - the correct way.

    just be careful when tightening the drain plugs,they are brass and crossdrilled.
    its not nessasary to remove them completly just back them out a couple turns.
    if you do break a head off when retightening you wont be an exclusive club member.
    its also why we stock them.
    luclily the broken part is easy to back out of the fuel bowl.
    and I DO use manuals. its why I dont get to involved with actual specifications unless I am at work and have a service manual handy.
    over the years I have seen many engine failures from all brands.
    the goal is to identify what caused the failure so it does not happen again.
    suzuki has some very nice video courses,and instructor led, on piston failure analysis.

  4. #4
    Lieutenant Commander triumphrick's Avatar
    Join Date
    Jun 2008
    Masaryktown, Florida

    Default Re: Yamaha 90tlr - How to drain the carbs - the correct way.

    I owned one of those motors for almost ten '86 model. I fished that motor long and hard and one of the tips given me by the selling dealer was to keep a light spray of wd-40 on both the inside and outside of the motor and to always run the carbs dry.

    So, after almost ten years I never had an electrical, mechanical or fuel related problem. Those three carbs never had to come off the motor or to come apart.

    The motor was flushed regularly and got a new impeller and plugs every other year. Most of the time the impeller still looked new, even after a couple hundred hours. In the waning years I owned it, it began to heat up a little under a load. The buyer of my rig had the head pulled and corrosion removed and ran it for many more years.

    That experience with that motor back then has kept me a loyal Yamaha customer

    Good luck with yours!
    Captain OUPV

  5. #5
    Join Date
    Feb 2007
    Monroe NC.

    Cool Re: Yamaha 90tlr - How to drain the carbs - the correct way.

    Rodbolt and others are quite correct, however, and there is always one of those, I am in Monroe NC and never drain the carbs on my boats. I use Stabil and now the marine version, religiously, in all of my gas. I have done this for the past many years and have had no problem starting up in the spring. Tearing down the carbs as routine maintenance every couple of seasons reveals no shelac and minimal contamination, this probably due to my use of water trap filters on all the bigger motors along with the Stabil.

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