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  1. #1

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    Running on one cylinder

    Hello, My first time posting but have found this forum to be the best resource in the repair of my watercraft. My question, 1995 SLT 750 (Blue Fuji engine). It has been setting for about two years, I cleaned the tank, lines, fuel pump (new triple pump and lines on the way), new plugs and battery, ohm out electrical system according to manual (all looks good), cylinder compression 110 to 120 on all three cylinders. It runs but I can pull the #! and #2 plug wire with no change in engine performance, with a spark checker I cannot see a spark on any of the plugs but I can hear the spark when lifting the cap off the plugs, when I spray a little starting fluid down the carb (1 or 2) the engine picks up. How can I determined if the problem carb related or CDI or something else. Thanks, tried to keep it short.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk

    Did you remove, open, and clean/rebuild the carburetors?

    If not, then that is a likely problem area.

    Did you check for a small brass flow restrictor inserted inside the old return fuel line, about an inch from the carb?

    If your old fuel line had that restrictor, it needs to be installed in the replacement return fuel line.

    I see you can get it to start and run, but I will mention this anyway;
    Make sure the battery is strong. Polaris PWC really want a strong battery. Voltage while cranking should always be over 10.6 volts.

    The ignition in your Fuji engine fires all three spark plugs together, every time any cylinder needs spark.

    So you can swap plug wires around and see if the problem moves. You can tell which cylinders are firing by the heat they produce.

    Make sure the correct NGK spark plugs are installed.

    You can run it without water cooling for 10-15 seconds. Shut it down. Feel each cylinder. the cool ones are not producing power.

  3. #3

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    Thanks for the fast response. I have not done anything to the carbs yet, I'm a little intimidated by them. But I will read the manual until I am comfortable with them. I have not had much experience with 2 strokes but have been working on CNC and robots for about 28 years. They seem straight forward from what I have read so I'm willing and eager to learn. I have not changed the fuel lines yet but I did pull everything off, clean and inspect them, not much build up but new lines are on the way. I didn't know I could swap the plug wires to different cylinders, that will be helpful. How much fuel pressure (or vacuum) should I expect to see after the pump? My son reminded me that the last time we rode them (2 or 3 years ago) that this one lost a lot of power before we put them up, and I have not messed with them since. Many thanks to all the people that make this forum possible.
    P.S. I was going to order 3 carb kits from this website but they don't sell Polaris parts. I would like to buy from someone that supports this forum if you will help ID the correct parts I need I will get them on order.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Contact John Zigler.

    Polaris PWC Parts Sources

    Also, click the link in my signature. Lots of good reading

  5. #5
    ryandi2's Avatar
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    Quote Originally Posted by dmac61 View Post
    Thanks for the fast response. I have not done anything to the carbs yet, I'm a little intimidated by them. But I will read the manual until I am comfortable with them. I have not had much experience with 2 strokes but have been working on CNC and robots for about 28 years. They seem straight forward from what I have read so I'm willing and eager to learn. I have not changed the fuel lines yet but I did pull everything off, clean and inspect them, not much build up but new lines are on the way. I didn't know I could swap the plug wires to different cylinders, that will be helpful. How much fuel pressure (or vacuum) should I expect to see after the pump? My son reminded me that the last time we rode them (2 or 3 years ago) that this one lost a lot of power before we put them up, and I have not messed with them since. Many thanks to all the people that make this forum possible.
    P.S. I was going to order 3 carb kits from this website but they don't sell Polaris parts. I would like to buy from someone that supports this forum if you will help ID the correct parts I need I will get them on order.

    what are the compression numbers on all three cylinders? when you lost power that might have been from burning down a piston from a lean condition.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ryandi2 View Post
    what are the compression numbers on all three cylinders?...
    Quote Originally Posted by dmac61 View Post
    ...cylinder compression 110 to 120 on all three cylinders...

  7. #7
    ryandi2's Avatar
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    Quote Originally Posted by K447 View Post

    id say re check to confirm.. 110 is low

  8. #8

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    I rechecked my compression, #3 (PTO) 115psi (this is the cylinder that is running), #2 118psi and #1 115psi. I checked battery voltage (new battery), it has 12.06V but drops to 9.6 Volts when cranking. I did talk with John, he suggested cleaning the carbs before ordering kits. Nice to know someone is willing to help you solve your problem instead of just selling parts

  9. #9
    ryandi2's Avatar
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    those numbers are low, but you need to get a better battery it needs to be above 10.6 while cranking! this will be a huge issue..

    get a new battery and check compresion after that.. i checked compretion once with a low battery, wanted to know the differance... i had 119 on all cylinders.. but full battery they are at 130 ish

  10. #10

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    Can I boost the battery with jumper cables or charger to see if this makes any different? I only ask because I have to drive about an hour to return this battery, if it's bad.

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