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  1. #1

    2003 msx 140 surges, stumbles, boggs

    I have a 2003 MSX 140 HO purchased used last summer with 93 hours. Ran great first couple of trips then fuel pump quit. Replaced fuel pump. Got it going again. Rode a couple more times, no problems. Put it up for winter, got it out last weekend started riding again. Now having problems again. It runs great first 30 minutes or so. Then begins to miss a little, then a lot, surges, starts bogging, eventually shuts off. However, starts right back up, takes off like a rocket, runs great for a few minutes no problems then starts surging, missing, bogging again. When the symptoms begin, sometimes you can back off the throttle, and problem clears up but when you get back in full throttle symptoms return. Machine has new plugs, replaced TPS, EMM is hot to the touch but there is nothing blocking water flow through cooling lines. What else should I be looking for?


  2. #2
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    Emm should not be hot. Are you sure there is water flowing through it?

  3. #3
    Yes. Disconnected the hose from EMM to rear of jet ski (I assume this hose discharges water back into lake) started it up while in water and water flowed through EMM with not problems no blockages. What was odd was the hose I disconnected going from EMM to rear of ski appeared to be also pumping water back into the EMM while ski was running. Is that normal? I thought the EMM got its water channeled through the stator and back out the rear of ski.

  4. #4
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    Quote Originally Posted by D3210 View Post
    Yes. Disconnected the hose from EMM to rear of jet ski (I assume this hose discharges water back into lake) started it up while in water and water flowed through EMM with not problems no blockages. What was odd was the hose I disconnected going from EMM to rear of ski appeared to be also pumping water back into the EMM while ski was running. Is that normal? I thought the EMM got its water channeled through the stator and back out the rear of ski.
    Check that hose more carefully. I have seen the hose trapped under the battery, preventing water flow.

    It is also possible someone has messed with the EMM hose configuration, possible it is not properly connected to where it should be.

  5. #5
    Ran ski again this morning. I rechecked EMM cooling lines to make sure no obstruction, crimping etc. Removed thermostat/pop off valve to see if there were any corrosion, looked good. Checked and cleaned exhaust cooling orifice, as well as hose. It all looked good. I decided to remove thermostat to see if it might be sticking closed. Ski ran perfect for about 30 minutes or so. Than began missing and stumbling. Took seat off, checked EMM for excessive heat. It did seem to be cooler than yesterday. While idling, I pulled the discharge hose from EMM to make sure water was flowing through, looked good. Pulled hose off exhaust cooling orifice, water flowing with no obstruction. I did notice when I turn ski sharp left or right I could make it stumble as well. However, all was good up until 30 minutes into ride. Any suggestions?

  6. #6
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    Quote Originally Posted by D3210 View Post
    Ran ski again this morning. I rechecked EMM cooling lines to make sure no obstruction, crimping etc. Removed thermostat/pop off valve to see if there were any corrosion, looked good. Checked and cleaned exhaust cooling orifice, as well as hose. It all looked good.

    I decided to remove thermostat to see if it might be sticking closed. Ski ran perfect for about 30 minutes or so. Then began missing and stumbling.

    Took seat off, checked EMM for excessive heat. It did seem to be cooler than yesterday.

    While idling, I pulled the discharge hose from EMM to make sure water was flowing through, looked good.

    Pulled hose off exhaust cooling orifice, water flowing with no obstruction.

    I did notice when I turn ski sharp left or right I could make it stumble as well. However, all was good up until 30 minutes into ride. Any suggestions?
    The thermostat does not affect EMM temperature. Aside from diagnostics, the Ficht engines require the thermostat to maintain engine temperature within the expected range. Excessive cooling is not helpful with these engines.

    The thermostat only affects low RPM engine temperatures. At higher RPM the adjacent bypass 'pop-off' valve opens as the water pressure through the cooling system rises (water pressure comes from the jet pump and varies with engine RPM). The bypass valve should be checked for a worn or sticking plastic tip, which can happen over time.

    The EMM should never get warmer than mildly warm to the touch, depending on how warm the water flowing through it is. The EMM water flow is first warmed by heat from the stator cover water jacket, then goes through the EMM.

    That the engine stumbles when turning suggest a possible mechanical issue. It is possible there is a frayed wire or loose electrical connection somewhere. The throttle cable is affected by steering motion so a marginal TPS could be sensitive to tiny changes in throttle shaft rotation.

    Engine vibration also changes when turning so it could be sympathetic symptom.

    Since the EMM has already been hot to the touch, which is much warmer than normal, my instinct is that it may well need repair. These are known to often need repair as they age due to certain electronic components inside that are not as durable as one might expect. Once repaired the EMM tend to be reliable again.

  7. #7
    I will put thermostat back in, check for frayed wires, etc. Should I remove EMM from its outer case and inspect. Can it be tested? Would there be cracks, melted spots, burnt plastic? If so where can I send EMM to be repaired and how much would it cost to do so?

  8. #8
    Just want to say. With this forum I have learned a lot, and appreciate the valuable feed back. I made some more checks this morning. Compression in each cylinder show 110 to 115 psi per cylinder. Fuel pressure at Schrader valve shows 30 psi while cranking and 60 psi while running. What I've read in this forum is that the fuel pressure should be 20 psi or so. Are the fuel pressures too high? I also checked the temp sensor under the breather plate. The flame arrestor had not been trimmed and it cut into the top of the sensor through its plastic cover. How would the machine behave with this temperature sensor obviously damaged?

  9. #9
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    Quote Originally Posted by D3210 View Post
    Just want to say. With this forum I have learned a lot, and appreciate the valuable feed back. I made some more checks this morning. Compression in each cylinder show 110 to 115 psi per cylinder.

    Fuel pressure at Schrader valve shows 30 psi while cranking and 60 psi while running. What I've read in this forum is that the fuel pressure should be 20 psi or so. Are the fuel pressures too high?

    I also checked the temp sensor under the breather plate. The flame arrestor had not been trimmed and it cut into the top of the sensor through its plastic cover. How would the machine behave with this temperature sensor obviously damaged?
    I suspect your pressure measuring gauge is not accurate. The stock Polaris Ficht fuel pump can barely generate 30PSI so it seems unlikely that the 60 PSI number is correct.

    Compression numbers seem a little low but this may also be due to gauge inaccuracy. If all three cylinders are consistent then compression may not be a concern.

    Ficht engine should start and run with the air temp sensor unplugged. The sensor connector plug has two locking ears that are tricky to release since it is tucked up underneath the base plate of the flame arrestor and hard to get at. A mirror and light or perhaps some mobile phone photos can help you see what you are working with.

  10. #10
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    Did you ever get the problem figured out?

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