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  1. #1

    Join Date
    Apr 2011
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    Titusville, Fl.
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    '99 Yamaha GP760 won't start in water!

    I have a '99 Yamaha GP760 that runs great at the house, but when I drop it in water it will turn over - but it won't start??? Any ideas???


  2. #2

    Join Date
    Nov 2009
    Location
    NC
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    +1
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    More info.

    Will it start at top of ramp?
    Has this happened only once?
    Fuel sitting from last year? Did you treat it?
    Could the ride to water be jiggling something loose?
    Spark plug wires ok?
    My '97 GP760 is notoriously hard starting. Pull a plug and squeeze an eyedropper of gas into cylinder, put plug back and it should fire.

  3. #3
    is this all in the same day? You start it and it is running at your house and in the same day you get to the water it won't start or how long is between it running and when you got it to the ramp?

  4. #4

    Join Date
    Apr 2011
    Location
    Titusville, Fl.
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    7
    The first problem we had was when we went to an island 1/2 mile offshore and 15 minutes later we went to leave and it spit and sputtered on the first 3-4 attempts to start it, then it would just turn over and over but wouldn't hit a lick. After 20-30 minutes of choking and trying to get it to start we towed it back in and once I got it home I tried all the obvious things: installed new spark plugs, checked the fuel filter and lines, checked the ground - nothing worked. After it sat for 5 days it started right up and ran great. I didn't know what to chalk it up to, but was really happy it was running again. I started it 5-6 times then ran it on the hose for 15 minutes, running great. 2 days later we went to take it out again. I started it 3 times at the house and then again 5 minutes from the river when we stopped for gas and it was running great. We unloaded it at the ramp, went to head out and it would turn over and over but wouldn't hit a lick. Loaded it back up and took it straight to a local shop. A few days later the mechanic started it at the shop and it fired right up several times. He took it to the ramp, dropped it in the water and when he tried to start it, same crap - turning over but would not start. He loaded it back up and took it back to the shop and a couple days later it fired right up and ran great. He took it back to the water and this time it started in the water and ran great for 10-12 minute then stalled and wouldn't start back up. He put it back on the trailor and pulled it into the parking lot and got it running. He thinks it's fuel but not the carbs because of how great it runs on land. He's leaning more toward fuel supply, maybe a fuel line collapsing. So my next move is to install a new pick up line and filter and go from there. It seems that at the house or shop it will run awesome all day, but when it's in water under a load it turns over but won't start.

  5. #5
    Perhaps it could still be your carbs? Just like you can't test for bogging on the trailer, it needs to be under load in the water. Maybe your carbs are weak and or dirty but you can just get enough to start it on land but in the water another story.

    When was the last time the carbs were rebuilt?

  6. #6

    Join Date
    Nov 2009
    Location
    NC
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    Is this your only ski?

    Once on water, try the dropper of fuel into cylinder. If it fires even briefly it will tell you that it's a fuel delivery problem.

  7. #7

    Join Date
    Apr 2011
    Location
    Titusville, Fl.
    Posts
    7
    I'm sure the carbs could use being rebuilt. We've had it 2 years and it hasn't been done by us, but we are good friends with the guy we bought it from so i'll ask him about it. He is the original owner. This is the first time we have had problems with this ski, it has always started up and ran great. You know, a couple weeks before we had these problems it started to rev up then drop down on it's own. The first time I noticed it doing that was after we came home from a day on the river and while it was running at idle on the hose at the house it would rev up to 3,500 then drop off to idle and right back up over and over really quick to where the tach needle was bouncing. Was this a warning sign of the problem we're having now??? And no, this is not our only ski. My wife has this '99 GP760 and I have a '99 XL1200 LTD. I am the one who had another post about the primer bulb toyterrific! The dropper of fuel is a good idea, i'll try that. Thanx to you both for your help.

  8. #8

    Join Date
    Nov 2009
    Location
    NC
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    I need to pay more attention to who posts, don't I?
    I actually bought a plastic syringe with a 4" length of clear tube on the end that I keep in the ski at all times. Start them up at home with the "gas in the cylinder" method. Try to start again at ramp before putting in, use syringe if you have to. Let it run for about twenty seconds. They should then start on their own once on the water. When we stay overnight at the lake I don't even bother trying without syringe assistance on that first morning start. (I also have a primer kit for the 760 but haven't had time to install that one yet.)
    If you want to try a carb rebuild on your own the 760 will be much easier than the 1200.
    Make sure you get genuine Mikuni kits and find a factory service manual to download. There are incredibly knowledgeable and helpful guys on this site if you have questions.
    (You really should give your wife the xl1200 since it rides much smoother. Don't tell me she drives the older car, too!)

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