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  1. #1

    03 msx 140 fuel problems

    Hello!

    Bought a 03 msx 140 last week, my first ski...

    Ran great on the first day, until we supposedly ran out of gas, (still had a half tank) got it out of the water filled it up(chevron 91) and fired up perfectly.
    The next trip ran great for a couple hours, then, at about half tank, it wouldnt stay on anymore.

    Found this site, and did the following:

    Changed sparkplugs(the correct kind)
    New battery
    Compression 125 119 124
    Tried to check fuel pressure but didnt get a reading because the jetski started up perfectly and gas just squirted out the valve...

    Thought I had fixed the error, so took it out again, filled it with shell 91 and ran great(slight hesitation every once in a while). At half tank the same thing happened, wouldnt stay on.
    Got home filled with gas and started perfectly!

    I asked previous owner if he had worked on or replaced the original fuel pump and he said no.

    Im not sure how exactly the fuel pump works but I figure its one of two things:
    1. The actual pipe that sucks in the gas has shifted in the tank and now sits in the upper half of the tank.
    2. The fuel pump is weak and cant maintain enough pressure at half tank(too much empty space?) To give the engine any more gas...

    Could someone explain how the fuel pump works and share some insight on what I should do next?

    Thanks for this priceless forum!


  2. #2
    ripcuda's Avatar
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    Welcome to GH!

    Couple things to check. You need to check your fuel pressure. And plan to repair the common-to-fail fuel pressure regulator inside the fuel tank even if it hasn't failed yet. Because it will and when it does, it will likely kill your engine. The schrader valve Tee where you check the fuel pressure. Are you saying that when you take the cap off, it sprays fuel? If so, the internal valve must have blown out (does happen)... and this needs repaired. Either with a new good replacement Tee... or remove that Tee and put in a splice. If you plan to remove the Tee and go with a splice, first get a pressure reading. You might try and hook the gauge up prior to turning on the ski to get a fuel pressure reading. Keep lots of rags handy to catch any gas and use caution. Let us know what fuel pressure reading you get.

    Another possibility based on your description... could be a stuck air vent check-valve on the fuel tank. As the tank drains... the valve isn't letting air in to replace the fuel that left so the tank develops a strong vacuum internally... eventually becoming strong enough to counter the fuel pump trying to suck fuel out. I would inspect both in-valve and out-valve (breather valves) for the fuel tank. Or you could run it again until it won't run (half tank) then try opening the fuel fill cap. If there is a whoosh of air into the tank... and then it starts and runs again. You've definitively found your cause (stuck vent valve).

    Those are my initial ideas. Smarter Direct Injection experts will likely chime in.

    Cheers!

  3. #3
    I checked the fuel pressure with engine running... no reading. Clamped return hose and gauge stopped at 90psi... thats too much right?

    Took a picture of a third hose that comes off the top of the fuel tank... is this the air check breather valve?

    Going to take apart fuel tank to check fuel pressure regulator... will probably use cotter pin method...

    Its wierd though, im not getting any of the symptoms that usually accompany a failed fuel pressure regulator, no display warnings, still have plenty of engine power...

  4. #4
    ripcuda's Avatar
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    Something is not right with your fuel pressure reading. At idle... you should see ~20-22 psi fuel pressure at the Tee in the supply line. If you clamp off the return line (one w/o Tee) it should show ~30s. The fuel pump in the MSX 140 isn't capable of 90 psi pressure... so double check your pressure test again.

    The ECU doesn't have a fuel pressure sensor... so when the FPR fails and pressure drops way low... the ECU doesn't know and does NOT throw any warnings. And folks who have had this happen often don't report really noticing the change in the engines performance. Until the engine melts down the PTO cylinder and it dies.

    Good FPR fix how-to: http://www.greenhulk.net/forums/show...084#post852084

    MSX 140 info: http://polarispwcknowledge.shorturl....jected-engines

    In the FPR fix link above... scroll down to the pics of the top of the fuel pump canister where the fuel lines/vent connect. The line that connects to the side pointed connector with the blue clip on it... is the fuel tank vent. That line will have a Tee in it with 2 ends. One hangs inside the hull with a check valve. This is the air-IN check valve and the one I suspect might be causing you issues. The other hose end will connect to the hull and vent outside. This is the air-OUT check valve... venting any gas fumes from pressure build-up externally. Check them both.

    Cheers!

  5. #5

  6. #6
    Tried to re-attach FPR using the Cotter pin method, but I made the groove too high on the FPR connector and the seal is not very air tight...
    When I blow into the return valve air is passing through quite easily... I will just have to buy a universal adjustable FPR, I Saw someone recommend one in another feed...
    http://www.ebay.com/itm/Universal-Re...3D872751821653

    At least I cleaned out the gas tank, it was dirty.

    I think the previous owner may have switched the fuel hoses going from the schrader valve to the gas tank... in the picture the top hose has the Schrader valve but the top hose is thinner than the bottom one, isn't the supply hose supposed to be slightly larger than the return hose? Which hose is supposed to be the Supply, the one that runs through the top of the injectors or through the bottom?
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  7. #7
    ripcuda's Avatar
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    Quote Originally Posted by alomeli View Post
    Tried to re-attach FPR using the Cotter pin method, but I made the groove too high on the FPR connector and the seal is not very air tight...
    When I blow into the return valve air is passing through quite easily... I will just have to buy a universal adjustable FPR, I Saw someone recommend one in another feed...
    I understand what you did. As I have done the cotter-pin method of FPR repair also. Instead of going the external FPR route (which is not recommended)... why not just do the other recommended FPR repair method with the threaded-in barb?
    http://www.greenhulk.net/forums/show...=1#post2424525

    At least I cleaned out the gas tank, it was dirty.

    I think the previous owner may have switched the fuel hoses going from the schrader valve to the gas tank... in the picture the top hose has the Schrader valve but the top hose is thinner than the bottom one, isn't the supply hose supposed to be slightly larger than the return hose? Which hose is supposed to be the Supply, the one that runs through the top of the injectors or through the bottom?
    The hoses and schrader valve in your picture are correct. Top ports are supply (w/ the schrader valve in it)... lower ports on injectors are the return.

    Did you check your fuel tank vent check-valves?

    Cheers!

  8. #8
    I was able to finally get the FPR re-attached with minimal air leakage, however my fuel pressure reading still seems to be off, with one of those stick gauges (where the plastic comes out to give you the psi reading) its stopping at 40 psi, this happened with two different gauges, one of them brand new. I also bought a dial gauge and the needle seems to jump form about 25 psi to 50 psi very rapidly, here is the video for reference...



    What should i try next?

    ill take a look at the breather valves right now

    thanks

  9. #9
    I checked the breather valves, the IN seems to be fine, if it was stuck it isn't any more... I am not able to get air through the Out with just my mouth, using an air compressor I was able to get air going through at about 20psi, but didn't test at lower pressure, is that good enough?

  10. #10
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by alomeli View Post
    I checked the breather valves, the IN seems to be fine, if it was stuck it isn't any more...

    I am not able to get air through the Out with just my mouth, using an air compressor I was able to get air going through at about 20psi, but didn't test at lower pressure, is that good enough?
    Pressure relief check valve (vents the fuel tank out to rubber breather fitting on upper hull) should open with just a couple of PSI, less than 3 PSI typically.

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