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  1. #1
    The powder Man!! ashelgren's Avatar
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    1994 750sl shuts down

    I just bought a 94 750sl it was not ran for a few years fired up sounded great on the trailer once I got it in the water it was a differnt story. This is my first pwc by the way but I am good working on motors and fixing things. On the water it ran good for about 5min. and stalled it did this over and over so I put the triple fuel pump on it lots of new hose but not from the water seperator to tank. Carbs are rebuilt the guy bought them off ebay 100.00 and put them on for me they look a look a little differnt it has a extra nipple on the supply side. After the triple pump was installed in the same location as oem I took it back out it ran better but if I went pass half throtle it would want to die it would start right back up no problem. I rode it for about an hour like this display gauge does not work so I don't know what rpm or if any lights were on does this pwc have a limp mode? comp. on all cylinders was 130psi. Also their is no air filter is it supposed to have one their is only a metal mesh grate on top of carb and a air box. Thanks


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Green Hulk!
    Quote Originally Posted by ashelgren View Post
    I just bought a 94 SL750 it was not ran for a few years
    There are lots of things you should check to ensure it will be reliable for you.

    fired up sounded great on the trailer once I got it in the water it was a different story. This is my first PWC by the way, but I am good working on motors and fixing things.

    On the water it ran good for about 5min. and stalled. it did this over and over so I put the triple fuel pump on it lots of new hose but not from the water separator to tank.
    You need to check whether you have a fuel return line flow restrictor. Without the restrictor, which for some model years was inside the carbs, and in other years was a small metal fitting inside the fuel return line, you will have low fuel pressure.

    Since you are not running the original carbs or fuel lines, the restrictor may not be present. If you can, connect a fuel pressure gauge after the fuel pump, and verify you have between 4 & 6 PSI at WOT, and about 2 PSI when idling. Lower pressures would indicate the restrictor is missing, or the fuel pump is not working properly.

    Carbs are rebuilt the guy bought them off eBay 100.00 and put them on for me. they look a look a little different, it has a extra nipple on the supply side.
    That may mean the carburetor jetting is not the same as stock. What happened to the original carbs?

    After the triple pump was installed in the same location as OEM I took it back out it ran better but if I went past half throttle it would want to die it would start right back up no problem.
    I rode it for about an hour like this
    Be careful. Running these engines with inadequate fuel flow can cause lean burn, with high piston temperatures and engine damage.

    Display gauge does not work so I don't know what rpm or if any lights were on
    Check the MFD fuse inside the electrical box. Replace with a 1/4Amp glass fuse, available from Radio Shack, etc.

    does this PWC have a limp mode?
    I doubt that would be causing your problem.
    Limp mode limts RPM, but does not cause the engien to die.

    Comp. on all cylinders was 130psi. Good.

    Also there is no air filter. Is it supposed to have one?
    There is only a metal mesh grate on top of carb and a air box.
    That is all the early Polaris models had - the flame arrestor is that flat metal plate with all the small holes in it.
    Are you burning old gasoline?

    Have you checked inside the tank for water?

  3. #3
    The powder Man!! ashelgren's Avatar
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    750sl shut down

    I drained the tank and put fresh gas in it no water in tank has water sep. inline. Heads felt cool even after riding for awhile I did see water on the metal grate flame arestor their was about an inch of water in the hull maybe it sucked it up. The fuse I looked at it unlike any fuse I ever seen it looks like brown link inside it's not metal like a car fuse how do you tell if its blown the display has a little fog on the screen to. For the orig. cabs. I have them one has A little corrision in it and the choke is stuck but the other two are fine I was thinking about rebuilding it because it an oem part I like to stick with oem on major parts like that. You don't think with the new fuel pump it floods the engine is that posible? Thank you again!!

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ashelgren View Post
    ...I did see water on the metal grate flame arestor their was about an inch of water in the hull maybe it sucked it up.
    Do you have the plastic cover over the engine to drive shaft coupler? If it is missing, the spinning coupler can sling water spray around the engine, which is not good.

    The fuse I looked at it unlike any fuse I ever seen it looks like brown link inside it's not metal like a car fuse how do you tell if its blown?
    You can check it with an ohm-meter. A good fuse reads zero ohms between the two ends, when you test it OUT of the boat.

    Since it is such a fine wire inside the fuse (1/4 Amp), some fuses have a non-metallic piece inside to support the fine fuse wire. Hard to see, but usually that wire is wound in a spiral along the supporting bar.

    If yours is bad, it doesn't really matter whether the new fuse has just the fine wire, or the thicker support bar inside. Just don't install a fuse rated for more than 0.25 Amps.

    the display has a little fog on the screen too.
    If you have moisture right inside the MFD, that could cause it to not work properly. If just the clear plastic faceplate itself is faded or scratched up, then the display could still be OK.

    ...You don't think with the new fuel pump it floods the engine is that possible?
    The fuel pump will not deliver such excess pressure unless it is hooked up incorrectly, or the fuel return line is blocked.

    Since your problem occurs as the throttle is opened wider, the problem is likely to be LACK of fuel, not excess fuel.

    Download and review the Service Manual, think about checking the fuel pressure, and think about pulling those carbs apart to confirm what jet sizes are installed in them.

    Since they came from eBay, you cannot even assume they are all the same jetting, so you would have to open up all three.

  5. #5
    The powder Man!! ashelgren's Avatar
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    their is no water in tank I cleaned all the old gas replaced the fuel filter the old carbs. I have but the choke is stuck on one carb. so it needs some fixin which I would like to do so I can put the orig. back on do you think the new fuel pump needs to be mounted lower the ski runs great at half throtle but any more than that and it dies and starts right back up the motor is staying cool I put my hands on the heads warm but not hot I can keep my hands on the head for a minute before I have to pull it off. I will upload pictures of the carbs tomorrow so you can see the difference between them. should I try to tune them like the oem ones? and I guess I would have to do that on the water? I will look for the restrictor to I am going to replace the rest of the fuel lines tomorrow don't trust them they are the orig. the shut off switch is completely rebuildable right if I take it a part just new o-rings and maybe a little lube. Thanks again!!

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ashelgren View Post
    ...the old carbs I have but the choke is stuck on one carb.

    ...do you think the new fuel pump needs to be mounted lower?
    The best place for the fuel pump mounting seems to be just above the level of the pulse fitting on the crank case, with a short pulse line. Others have mounted the pump higher, and it seems to work OK there too.

    the ski runs great at half throttle but any more than that and it dies and starts right back up

    the motor is staying cool I put my hands on the heads warm but not hot I can keep my hands on the head for a minute before I have to pull it off.
    Sounds plenty cool to me, as long as all thre cylinders are similar in temperature.

    I will upload pictures of the carbs tomorrow so you can see the difference between them.
    Others will be more expert on Mukuni carbs and Fuji engine issues than I. Most are outside enjoying their long weekend, I suspect.

    Should I try to tune them like the OEM ones?
    The eBay carbs can only be tuned for your engine if the metering jets inside are the same sizes as OEM stock, or very close.

    Without actually looking inside, you won't know what jets are in those carbs (unless you are certain which Polaris year and model they came from).

    Also, those eBay carbs may not actually be in good shape and clean internally. Don't assume they are good just because someone said they were good.

    and I guess I would have to do that on the water?
    Yes, you must do the carb tuning with the jet pump in the water. You can do part of it with the PWC strapped to the trailer (backed down the ramp into the water), which makes it easier to work on the engine that when it is floating.

    I will look for the restrictor to I am going to replace the rest of the fuel lines tomorrow don't trust them they are
    the orig.

    the shut off switch is completely rebuild-able?
    If I take it a part just new o-rings and maybe a little lube.
    I believe that is the case.
    My Polaris do not have the fuel shut off, and I have not rebuilt one myself.
    Do you see any air bubbles inside your fuel lines (presuming they are transparent hose material)?

    The fuel lines to the engine should just have fuel in them, not air, especially when the engine is running. If you see air, you may have an air leak somewhere before the fuel pump inlet.

    The fuel selector switch seals can get leaky with age, and let air into the fuel line when the engine is running.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow I am glad there is no echo in here...

    Well, I have actually been outside most of the time today, working on both my Virage TXi, but this is the first time I have been the ONLY registered GH member who is online!

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    Hope everybody's July 4th was a good one!
    See you all online later...

  8. #8
    The powder Man!! ashelgren's Avatar
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    I got the pictures the carbs. look really clean inside like new my new problem now is that I read a thread that said the fuel suppy line is the bottom fuel rail and return the top mine are reverse!!!! I just wanted to confirm that with some one so can switch that asap if its wrong I wish I knew more but its all new to me this is my first ski and I love it. I also have a dirt bike and a quad I do all the work on those also I belive in doing it your self the only way to learn. The fuel orfice in the return line is non-existent on my ski its in the carb. but I have not checked the fuel psi yet I want to make sure the return and supply are on right first. Can I put the psi gauge on one of the extra outlets on the carb. that are caped now?
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  9. #9
    The powder Man!! ashelgren's Avatar
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    Quote Originally Posted by ashelgren View Post
    I got the pictures the carbs. look really clean inside like new my new problem now is that I read a thread that said the fuel suppy line is the bottom fuel rail and return the top mine are reverse!!!! I just wanted to confirm that with some one so can switch that asap if its wrong I wish I knew more but its all new to me this is my first ski and I love it. I also have a dirt bike and a quad I do all the work on those also I belive in doing it your self the only way to learn. The fuel orfice in the return line is non-existent on my ski its in the carb. but I have not checked the fuel psi yet I want to make sure the return and supply are on right first. Can I put the psi gauge on one of the extra outlets on the carb. that are caped now?
    The carbs. that are monted to the ski have an outlet or inlet on one side and one on the other side the oem carb. has both inlet, outlet on same side does anyone know what the ones on the craft are and what is suppy an return?

  10. #10
    Moderator beerdart's Avatar
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