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Thread: ? on my Yamaha 2 stroke hesitation

  1. #1
    grizzeyes
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    Default ? on my Yamaha 2 stroke hesitation

    I read what bizimocha said about winterizing 4 strokes and thanks for the heads up about using 91 octain non-oxygenated fuel. Maybe this is my problem!! anyway, I have a 2000 TLRY 40 hp 2stroke yamaha that is like new with the factory plugs still in it and the mechanic said it's hardly been used.

    Once on plane in my 16ft sled, once I'm topped out the rpm's will all of a sudden slow down as if someone was easing up on the throttle. The boat will just go at a certain speed about 3/4" but no faster. then I'll ease up on the gas to a slow cruise then hit it and the jets open up and i'm good to go but then after about 15 seconds it will do the same thing.

    Sometimes it sounds a bit sick and vibrates more than usual when it's idling so i'll squeeze the primer bulb and rev the motor a tad.

    About every 3 or 4 days I open the fuel seperator valve to drain a bit of gas but as far as my trained eye can see, i haven't seen water mixed in yet. Should I open the drain a bit every time before leaving the house?

    going to defanetly make sure I keep the carbs free of the yellow tarnish. I have a bottle of yamaha fuel stablizer, guess it wouldn't help to add some to the tank. Is there anything I could spray up into the carbs or other area's to clean it up or will the good gas and stablizer do the work itself?

  2. #2
    Moderator JDM's Avatar
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    May 2006
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    Default losing rpm...

    I have remdied the problem of this by installing and electric fuel pump in the feul line...befor the ine goes into the water separator. Switched it to bea able to tun it off when the engine is not running. Sounds the same as my problem...air leak in the fuel line at the connector or pinhole in the line somewhere...this took care of it for me.

  3. #3
    Member Snagger's Avatar
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    Default

    Possible fuel pump issue, had same prob on my port engine, Yamaha 150 twostroke.

  4. #4
    grizzeyes
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    forgot to mention that sometimes i'll be crusing along wide open when it doesn't really keep me wide open i'll feel a thump and i always thought that my prop would be hitting a dead humpie floating down river. this happened yesturday and after the "thump" the motor kicked in apparently and the boat was moving much faster. I appreciate the help. dang mechanic is hard to get a call back from. don't know why but i've left 2 messages in 2 weeks and not a call back.

  5. #5
    New member
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    Apr 2006
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    Default

    I agree that it sounds like a fuel problem. It could be air getting in, ubstructed fuel line, clogged fuel filter, fuel petcock not fully open, or fuel pump. Check the simple things first.

  6. #6
    grizzeyes
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    i placed an order for the owners manual over 30 days ago but yamaha still has it on backorder. The yamaha shop over here said it sounds like the sink n link. he said it's a delecate procedure and if i dont' know what I'm doing can really screw things up.

    I checked with a gas station yesturday and she spoke with the oil techs up north who deliever their gas and they told her Alaska has no non-oxygenated gasoline. I put 12 gallons of 90 octane into the tank and didn't see a difference. guess it's time to spend some money.

  7. #7

    Default Check this site out first

    This site is super for getting answers to questions like this. http://www.yamahaoutboardparts.com
    The nice thing is that you can get the parts from them to. awesome website
    John

  8. #8
    grizzeyes
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    Default

    excuse me I worded that wrong. here in AK we only have non oxygenated.

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