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  1. #1

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    96 STS wont stay running. Need help

    I cant seem to keep this running. I have to totally cover the carbs to get it to fire up and then I have to gag the throttle every 10-15 seconds to keep it running. I cant get it to fire up with reg choking. have to fully cover carbs for a second. guy I got it from said he had just rebuilt the carbs and replced fuel hoses. So far I have drained the tank and put fresh gas in. The fuel selectors seems to be working and flowing ok. I checked and made sure the hose was on that goes from the manifold to the carb. I pulled it off and turned the motor over, It felt like it was blowing. shouldnt i have vacuum?? any thoughts? could carbs be out of adjustment? What is the starting point on the high speed and low speed screws? turn all the way in and back out xx turns? thanks for any help you can give.


  2. #2
    steve45's Avatar
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    Check fuel filter, fuel pump, fuel pickups in the tank. Quite possible the previous owner botched the carbs. The hose is a pulse line, it transmits pressure pulses each time the piston goes up & down.

  3. #3

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    What do you mean by botched the carbs? I did check the fuel filter and fuel seems to be flowing freely from the tank and through the fuel switch. I checked comp today. both at 155. Could the carbs just be way out of adjustment?


    Quote Originally Posted by steve45 View Post
    Check fuel filter, fuel pump, fuel pickups in the tank. Quite possible the previous owner botched the carbs. The hose is a pulse line, it transmits pressure pulses each time the piston goes up & down.

  4. #4
    steve45's Avatar
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    The carb diaphragm/gasket assembly could be out of sequence, the lever arm could be bent, internal filter plugged, etc. Somebody may have 'tightened' the mixture screws, who knows? You'd be amazed at what idiots can do.

    I don't remember what the mixture screw starting points are (and I own five 750s), but if you start with about 1-1/4 on the high speeds and 1 turn on the low speeds, it should run.

  5. #5

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    I know its been a few weeks but vacation then back to get caught up at work took most my time. So Its still not running right. I checked the manual and it said turn high and low speed screws in and back out 1 turn to start. so I did. I also took the whole fuel system out of the equation and ran a fuel hose and fuel return to a small gas can in the foot well. still will not stay running. Has to be something with the carbs right??? just seems like its not getting the fuel it needs at idle. runs and sounds strong when revving

  6. #6
    steve45's Avatar
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    Carbs or fuel pump, most likely. Many people don't know crap about carbs and mess them up.

  7. #7

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    Is there a good thread on rebuilding these carbs?


    Quote Originally Posted by steve45 View Post
    Carbs or fuel pump, most likely. Many people don't know crap about carbs and mess them up.

  8. #8
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    Quote Originally Posted by steve45 View Post
    Many people don't know crap about carbs and mess them up.
    that's +1000

    You'd be amazed how much work I get from folks that spend half an hour describing how they rebuilt the carbs and just need my touch to "set it up right" like I'll give them the "trade discount"..... if anything it costs them far more as I replace every stripped screw and questionable part

    this to me is clearly a fuel pump/float arm height problem ( for starters)


  9. #9

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    Ok.....so I took apart the carbs and checked everything out. it all appears to be good. I was reading on another thread and long story short I backed out the low speed screws 4 turns and left the high speeds at about a turn and a quarter. It starts up and runs normally!!! BUT....If I let it idle for a few minutes then goose the throttle it bogs. If I feather the throttle or ease into it it then will rev up fine and continue to rev normal until I let it idle for a few min. Is it getting too much fuel? Should I turn the screw in a turn? Am I headed in the right direction?

  10. #10
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    did you check pop off pressure?

    guessing doesn't work and using a 4 turn out setting says you are guessing.

    guess what?

    you need to set carbs to factory specs to have a chance of getting it right.

    low speed start at 3/4 to 1 1/2 turns out. Assuming the carb hasn't been ruined by closing the low speed screw too hard.

    lightly bottom it then back out 1.5 turns.

    confirm pop off pressure or chase your tail for weeks.

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