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  1. #1

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    MSX 140 Rev issues

    My MSX 140 will not get up past 6200 rpm. Actually struggles to get over 5400 until i get the pump to cavitate then it'll climb to 6100/6200. If i get air after getting to 6 then it hits the occasional 7000.
    All 3 cylinders have between 120 and 125 PSI Comp and it makes 30 psi fuel pressure at the schrader valve. Plugs and piston tops are a nice tan brown so I'm baffled???
    Any suggestions where I should be looking next would be greatly appreciated


  2. #2
    martincom's Avatar
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    30 psi is high for fuel pressure---almost as if the return line were plugged. Is the fuel system stock? Are you monitoring fuel pressure when the failure occurs?

  3. #3
    Moderator HiPeRcO's Avatar
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    Have you measured the TPS voltage sweep?

  4. #4

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    So, hooked up the diagnostic and looks like the previous owner swapped out the EMM and did not reprogram the injectors. Additionally he installed the injectors but did not install the insulators between them and the heads. He had also not shimmed the engine plate to align the driveshaft/pump/coupler. Had the oil cranked almost wide open... Some guys should just leave those shiny wrenches hanging over their workbenches like trophies.
    Now, it's been a while since I played with these and never with this model of engine so info from those with experience would be appreciated. What is the optimum operating rpm range for this ski? Where can I get the programming coefficients for the injectors and has anyone had overheating/waterpumping issues? I bought 2 of these on a trailer; one running one not. Rebuilt the one that wasn't running, had the ECM redone went through it as best I could and everything looks good but it doesnt want to pump water through. All gaskets are good and properly installed, hoses as well and i've replaced the thermostat. only thing different is that the guy had removed the resonator and has a straight pipe. Could this be scavenging the water not allowing it to flow through the cylinders for some reason? I had pulled the brass plug out of the manifold while still on the trailer and ran the engine in the lake and it pumped water. As soon as I go for a ride , bring the revs up it seems to stop flowing to the cylinder. Could the pipe be cracked inside and exhaust be pushing in? Any ideas are appreciated

  5. #5
    casey67's Avatar
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    What makes you think it "seems to stop flowing" ?
    Some models had a thermostat and bypass valve installed on the end of the water bar/manifold. See if that has those parts and if stuck. By the way ,that is the water exit from the engine.

    The cooling water starts at the jet pump exit. On the inside, on the right should be a plastic screen. That needs to be installed and correctly for water to flow to the exhaust pipe/engine. Check those hoses from blockage..

  6. #6
    martincom's Avatar
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    What is the optimum operating rpm range for this ski?
    The EMM will limit the RPMs. In nearly all I've encountered, it will limit RPMs before the throttle flapper runs out of opening. I really haven't paid much attention to what RPM it limits at, but I'm thinking it is 6500, maybe 6800 RPM.


    Where can I get the programming coefficients for the injectors
    The injectors have a QR code on their label. If it hasn't been defaced by a pressure washer or something else, you can read them with a smart phone that has a QR code reader app. It has always taken me a fair amount of fiddling to get it to read. So persevere. Once read, the QR app will display the S/N of the injector and the four coefficients in plain English.


    anyone had overheating/waterpumping issues?
    No, not at all. The EMM 1/4" cooling hose discharges at a nipple at the hull exhaust outlet. If this has a straight pipe, I'm wonder what they did with the EMM cooling water discharge?

    The straight pipe is not a sound concept---but it sounds like that was more the norm than the exception of the previous owner. All the Polaris Direct Injected watercraft utilize an "open loop" fuel injection system. So the EMM will not compensate for air/fuel ratios dictated by an exhaust change. The programming map is assuming a stock exhaust. You'll want to locate a stock exhaust system to prevent things like melted pistons. I can help you out with this, if need be.

    You can find cooling system plumbing diagrams here.



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  8. #7

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    Because it overheats and there's no liquid in the manifold when I pull the plug once it's gotten hot. Yes I understand the flow and had put in a new thermostat

  9. #8

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    Quote Originally Posted by martincom View Post
    What is the optimum operating rpm range for this ski?
    The EMM will limit the RPMs. In nearly all I've encountered, it will limit RPMs before the throttle flapper runs out of opening. I really haven't paid much attention to what RPM it limits at, but I'm thinking it is 6500, maybe 6800 RPM.
    It won't crack 6200, sits about 61-6150 unless I get air and it cavitates


    Where can I get the programming coefficients for the injectors
    The injectors have a QR code on their label. If it hasn't been defaced by a pressure washer or something else, you can read them with a smart phone that has a QR code reader app. It has always taken me a fair amount of fiddling to get it to read. So persevere. Once read, the QR app will display the S/N of the injector and the four coefficients in plain English.

    And if the QR is unreadable is there a s/n database anywhere?


    anyone had overheating/waterpumping issues?
    No, not at all. The EMM 1/4" cooling hose discharges at a nipple at the hull exhaust outlet. If this has a straight pipe, I'm wonder what they did with the EMM cooling water discharge?
    All the hoses are routed and clear, blew them out with air. It's taking in plenty of water from the nozzle into the exhaust jacket and at low RPM on the trailer it fills the cylinders and exits the brass plug on the manifold but as soon as I ride it it heats up and seems to blow the water out of the cooling system like a cracked head or burned headgasket on a car would. That's why I'm wondering if anyone has ever had an exhaust jacket crack or if that's about impossible?/

    The straight pipe is not a sound concept---but it sounds like that was more the norm than the exception of the previous owner. All the Polaris Direct Injected watercraft utilize an "open loop" fuel injection system. So the EMM will not compensate for air/fuel ratios dictated by an exhaust change. The programming map is assuming a stock exhaust. You'll want to locate a stock exhaust system to prevent things like melted pistons. I can help you out with this, if need be.
    Got the resonator, will just need to get the rear hose, his was cut to fit the pipe. Thanks

    You can find cooling system plumbing diagrams here.


    a

  10. #9
    martincom's Avatar
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    Quote Originally Posted by Gone_Ridin View Post
    Because it overheats and there's no liquid in the manifold when I pull the plug once it's gotten hot. Yes I understand the flow and had put in a new thermostat
    Unless it is running, there will not be any cooling water in manifold. They are designed to be self draining. Also, there is no water pump. per se. The cooling water flow/pressure comes from the propulsion jet pump. There is an intake screen in the jet pump nozzle, that Casey67 spoke of, that taps off some of the propulsion water jet to circulate as cooling water. Check the screen for clogging or algae/corrosion build up. You may have to pull the pump nozzle to clean it. Also, be aware that there is a plastic orifice washer at the end of the intake cooling water tube, at the nozzle end, that will likel y fall out when you pulll the nozzle. Be sure to capture it and re-install it on assembly.

    You can also improvise a make-shift garden hose connection to the water intake tube to flush the cooling system and check the flow, while on the trailer.

    As a side note, you do not want to run these for more than 30 seconds out of water, even with a cooling flush hose connected. The driveshaft output seal is cooled by being submersed. Premature failure will result without that cooling water.

  11. #10
    martincom's Avatar
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    And if the QR is unreadable is there a s/n database anywhere?
    Not that I've ever heard of. Evinrude utlized the same FICHT system on their E-Tec outboards. They liked it so much, they actually bought it. When they went bankrupt, BRP acquired the assets. That was about the same time Polaris decided to exit the watercraft business. I can't help but believe one had something to do with the other--although that is pure speculation on my part. None the less, if there was such a database, BRP would have ownership of it.

    There are two identical labels, on each side of an injector. So if one is defaced, perhaps the other is OK. Everytime zi acquire a Direct Injected watercraft, I add the injector information to a database I maintain for each of my watercraft, along with diagnostic profile.

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