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  1. #11
    PWCToday Newbie cteff82's Avatar
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    Re: JS550 full rebuild

    absolutely. Ive had this ski for about 6 years now so i know it in and out pretty good. Thats why im stumped and asking for advice. I dipped the carb tonight and blew out every orifice on the carb at work. so tomorrow I'll find out if that makes a difference

  2. #12
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: JS550 full rebuild

    The 1986 550 came stock with a 44bn. But that year 44bn also had problems draining
    the fuel from the float chamber into the engine.


    Bill M.
    Horsepower == Speed, RPM != Speed



  3. #13
    PWCToday Newbie cteff82's Avatar
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    Re: JS550 full rebuild

    Quote Originally Posted by wmazz View Post
    The 1986 550 came stock with a 44bn. But that year 44bn also had problems draining
    the fuel from the float chamber into the engine.



    Bill M.

    i Put all new clear lines from carb to their respective spots and checked for pulse. Got good pulse. Itís not pulling fuel. So itís something with the pump even though I did a rebuild. There was a good amount of air bubbles I was sucking up as I tried to pull vacumm from the return hose off the carb. So somewhere itís pulling air in the carb.

  4. #14
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: JS550 full rebuild

    Did you leave the rev-limiter attached to the return line from the carb, or did
    you remove it?

    It's not going to run without it.

    Is the lever position level with the casting? If it is below the casting it will be difficult
    to start.

    Quote Originally Posted by cteff82 View Post
    So somewhere it’s pulling air in the carb.
    The most common place to pull air is the plastic inlet fuel fitting on the front of
    the carb. Overtime it gets concave shaped and the rubber gasket does a poor job
    of providing a good seal.

    I always flat sand parts of the fuel pump. A few pieces are never flat.

    Some times cleaning gaskets is a pain, but it is crucial to do a thorough job.

    Quote Originally Posted by cteff82 View Post
    Got good pulse. It’s not pulling fuel.
    So it’s something with the pump even though I did a rebuild.
    Assuming you correctly rebuilt the carb

    The fuel pump is the most common blamed component on jet ski carbs, when it is
    almost always the needle and seat that isn't opening.

    If there is no where for the fuel to go (like inside the float chamber), why would the
    fuel pump fill the fuel line with gas. The return line restrictor is itty-bitty ~.015".

    The 44bn has a defect in the pilot circuit that restricts vacuum from entering the
    float chamber. That pilot screw on the bottom right hand side, and atmospheric
    pressure is what opens the needle and seat.

    Did you replace the carb base gaskets, and properly remount the head stay?



    Bill M.

    2 things: Carb dipping is a bad practice and unnecessary. If you like to jump waves
    the rev limiter provides a valuable service.

    Also, removing rev limiters does not increase performance at all. But like Myself
    noted they can leak and cause the engine to load up.
    Last edited by wmazz; 02-24-2018 at 07:16 PM.
    Horsepower == Speed, RPM != Speed



  5. #15
    PWCToday Newbie cteff82's Avatar
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    Re: JS550 full rebuild

    I left the rev limiter intact and lines still connected because it needs that restricter. I always ran my ski with it connected and still plan to. Only disconnected the wires to rule out the issue.

    Rubber seal for pump inlet is new

    All gaskets were cleaned with 400 grit on a glass table.

    Pump was rebuilt corrected and looked over twice. The ONE thing I did not do and now think may be the problem is I did not do a pop off pressure test because I did not have a gauge for it. But now plan on making one to do the test. I simply installed the new spring that came with the kit from SBT.
    If the spring is too heavy and pop off pressure too high it would cause it to not open the needle and pull fuel correct? Should I cut a couple coils off the spring and see if that makes a difference?

    BTW I do have a bn38 on this at the moment. Not a 44. I have no pilot screw.
    Thanks!

  6. #16
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: JS550 full rebuild

    Will the engine start or run after primed?

    Quote Originally Posted by cteff82 View Post
    BTW I do have a bn38 on this at the moment. Not a 44. I have no pilot screw.
    I should have looked at the picture, that is a 82' - 85'. My favorite 550's. Did
    you know the stock impeller was ~19' up to 1986? Real torque monster and
    easy to ride. It was also more reliable than the 86' to 90' PP engines. A great
    ski to let a newbie ride without the fear they will need to towed back in.


    Bill M.
    Horsepower == Speed, RPM != Speed



  7. #17
    PWCToday Newbie cteff82's Avatar
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    Re: JS550 full rebuild

    I cant get the tank pressurized to help prime the lines. I attemped to suck the fuel from the return line through the carb but could not get the huge air bubble out of the "fuel in" line from the tank.
    I have a primer kit/choke delete that I'm installing tomorrow. I'm sure it will start with a the primer but most likely will not stay running because the carb does not seem to be powerful enough to fully prime the lines and pull fuel. We will see.

  8. #18
    PWCToday Newbie cteff82's Avatar
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    Re: JS550 full rebuild

    After deciding to finish my other projects I came back and looked over the carb again and noticed the New Needle lever arm was not perfectly level with the carb base and diaphram. Thus not allowing it to pull fuel. I tweaked it and hooked it back up and she fired up in 2 seconds....Now the ski fires up right away with no choke after sitting for days in the cold. GOOD TO GO.

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