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  1. #1

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    1999 stlx 1050 running rough. Feels like its missing.

    I've spent the last few days reading through the forum trying to figure what's going on and I can't do it on my own so I'm turning to forum for help.

    I have a 1999 Polaris 1050 stlx. I bought it about 3 months ago. When I purchased it I was told most everything had been gone through and or rebuilt. I was told the motor had about 20 hours on it since rebuild and that the carbs were gone through.

    The other day is the first time I had a chance to take it out to ride it (I've run it on the hose a few times in the last 3 months) and it would not start. It would try to start but would not run more than a second or two. Pulled the plugs and they were pretty oily so I put in new plugs. Made no difference. The MFD worked when I first purchased it but stopped working while I was trying to crank it.

    When I got it home and after reading suggestions from the forum I ran a direct fuel line bypassing the selector valve and water separator. I also disconnected the MFD. I noticed the accelerator pump was not supplying fuel to the 2nd and 3rd(rear)cylinder. I blew out the line and they started pumping fuel.

    At this point I could start it and it would idle roughly but it would idle. When I would give it throttle I could see in the carbs that it was backfiring flames down in the carbs.

    The fuel lines are the black type not the gray and I checked all hose connection for tightness. I pulled the plugs and ran each cylinder independently. I pulled the spark plug boots and checked the part that connects to the spark plugs and they all looked good.

    At this point I opened the electrical box that's in the nose and disconnected the two brown\tan wires to disable limp mode In case that was the issue. Made no difference.

    Next I checked the spark. I tried a ignition tester the type that is a spark plug type with a ground clamp. Couldn't see anything so I used a standard spark plug and could see spark. Seemed weak to me. Not as much as I would expect but it did fire.

    Now I'm puzzled but not beat yet. As it was running I was looking in the carbs and noticed the part that sticks out in the bore of the carb was dripping gas at a steady rate on the front cylinder. The middle cylinder was dripping much slower and the rear cylinder didn't look to be dripping at all. The front cylinder was much cooler than the other two after running. Almost cold to the touch. The middle cylinder was a little warmer and the rear was the warmest.

    So I pulled the carbs off and took them apart. They were clean like new inside. All the jets were free of gunk and the screens were undamaged. Fuel pumps were working properly. I blew air through everything and put them back on. On a side note when I removed the fuel lines to pull the carbs fuel shot out of the hose fitting on the tank like it was pressurized. I checked the one way valve on the vent line and it seemed to take a lot of pressure to get air to move through it. I removed the one way valve.

    Made no difference except the backfiring seldom happens now. . Put new plugs in again and ran it a few minutes and pulled the plugs. Front plug was black with oil. Middle plug was a little oiled and the rear was almost white.

    Compression test was next. Motor was warm when I did it. Front cylinder was 140. Middle was 135. Rear was 140.

    When running it now it idles rough is slow to rev up and is boggy when giving it throttle.

    I am sorry the post is so long but I wanted to be as thorough as I could.


  2. #2
    David Drkvampire2001's Avatar
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    Welcome to the hulk! We will for sure get to the bottom of your issues.

    back firing in the carbs could mean a few things. it could be a reed valve that is broken, or the ignition is off. both would also explain the rough idle. the 1050s( and 900s) both had issues with the original ignition system. Do you happen to know the part number of your CDI box? or do you know if you have a small grounding wire that comes from one of the your electrical boxes. to the battery? this would be an indication of the old and often problematic ignition systems.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    There should never be flames visible when looking down the carburetors, as there should never be flames inside the crank case.

    Check cylinder compression. All spark plugs out, throttle held wide open. Should be near 120PSI on each cylinder and all cylinders should be within 5% or so of each other.

    If that is good then remove the intake manifold and inspect the reed valves. They may have been damaged by the backfiring.

    Do you know if this engine has the updated ignition kit installed or still has the original ignition? The part number on the CDI will tell you. If there is a handwritten number on the CDI (may be on the hidden side) post it here.

    It is normal for the fuel tank to hold pressure, up to maybe 2.5 PSI. Always remove the filler cap to release trapped air pressure before removing fuel hoses.

    The carburetors may or may not need proper rebuild, which means replacing parts with genuine PEM rebuild kits. Cleaning the small passages usually requires spraying carb cleaner through, not just compressed air.

    One possible cause for backfiring is if the flywheel has twisted out of index on the crank shaft, shearing the woodruff key. This can be checked by removing the inspection plug from the top of the flywheel housing, then bring the front MAG piston up to TDC. The zero degree timing mark should be visible with piston at TDC.

  4. #4

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    First let me say thank you to everyone for the help. Going down the list. There is a ground wire from the battery to the black box.
    The module that the spark plug wires go to has a part number of 4010174.
    The other box in there has a number of 4060180.
    The stator housing and wires look new. The part number on the stator housing is wc105tcsp.
    The compression is 140,135,140. With the plugs out and throttle open.
    The carbs were clean as new. Air blew freely through all passages.

    Now the kicker. Opened the black box and water poured out of it.

    Will check the timing mark when it cools off outside 95 degrees today.

  5. #5
    BlueFishCrisis's Avatar
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    Quote Originally Posted by FloridaEdd View Post
    Will check the timing mark when it cools off outside 95 degrees today.
    http://www.greenhulk.net/forums/show...69#post2406669

  6. #6
    David Drkvampire2001's Avatar
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    The water will for sure cause an electircal issue, but that also confirms that you have the original non updated ignition system that could also be causing your issues.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by FloridaEdd View Post
    First let me say thank you to everyone for the help. Going down the list. There is a ground wire from the battery to the black box.
    The module that the spark plug wires go to has a part number of 4010174.
    The other box in there has a number of 4060180.
    The stator housing and wires look new. The part number on the stator housing is wc105tcsp.
    The compression is 140,135,140. With the plugs out and throttle open.
    The carbs were clean as new. Air blew freely through all passages.

    Now the kicker. Opened the black box and water poured out of it.

    Will check the timing mark when it cools off outside 95 degrees today.
    Get it dried out and examine for corrosion. Both the terminal board itself and all the wires that plug onto it.

    If you are lucky then all it needs it to be dried out and tested. If all turns out to still be good, spray or smear some fresh dielectric grease on the board and wire ends.

    The electrical box is supposed to have a large perimeter gasket (o-ring) to keep it 100% watertight sealed. Make sure the box will properly seal when it is closed up.

    Also look for corrosion under the protective dust cap on the CDI, if it has a programming port (DB-9 type).

    It sounds like that engine does still have the original ignition. If it turns out to still be in good working condition, you can defer doing the upgrade. At least for a while.

    Eventually most of these original ignitions seem to fail, so there is a risk of being stranded on the water somewhere. No predicting when or where, really.

  8. #8

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    Gonna let the electronics dry out good than see how it acts. Don't know how that much water could get in there. It wasn't just a few drops it poured out when I opened it.
    So we know the ignition has issues how about the carburators dripping different amounts of fuel?
    The wife's pushing me to part it out ( was not a pre approved purchase ) I'd like to fix it if I can it's a nice ski. Repainted and custom seat and handle bar cover.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by FloridaEdd View Post
    ... how about the carburators dripping different amounts of fuel?
    ...
    See my comments about carb rebuild kits.

  10. #10

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    How would I look up you're past comments on carburator rebuilding? Sorry I'm totally new to this.

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