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  1. #1

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    Polaris Msx140 starting problem

    Hi guys im hoping to get some help with the starting problem i have with my msx140..
    I purchased it couple weeks ago as a non running ski and was told that the EMM might have failed . I have since done a couple quick checks with my limited knowledge of these machines .. so far i have done a compression check ( 120 , 118 , 120 ) , im getting good strong spark at the plugs ( new spark plugs ) , fuel pressure is 19 psi when cranking , checked with an average quality gauge ..when i clamp the return line the pessure goes up to around 25 psi..
    When trying to start the ski it will sometimes fire and run for a few second and then stop ... a couple of time i was able to sart it and get some revs out of it but mostly it will just fire up and idle real rough for a few seconds then cut out..
    I should mention while doing this i have the water hooked up and runing at all times
    One thing i have noticed when i pulled the 12 pin plug from the EMM it looked like the plastic around number 5 and 10 pin looked burnt and discoloured as if it was getting hot around those 2 pins..
    Id like to get an opinion on where i should be looking , im prepared to send the EMM away for repair just want to make sure its not a different issue ..
    Thank you all in advance for any advice you can offer me ... cheers


  2. #2
    Click avatar for tech links/info K447's Avatar
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    Welcome

    Do NOT have the water running while testing. The cold engine is just fine to run for up to around 30 seconds without any water. There is risk of back flooding the engine with exhaust water when engine is not running and garden hose water is flowing.

    I have posted a few months back about a 1999 Genesis i that, among other things, had a burned Deutsch 12-pin connector contact at the EMM. Refer to that thread for photos and repair techniques.



    EMM failure can happen, but note that the MSX 140 EMM have some differences in failure modes compared to the older Genesis and Virage EMM. C89 is not a weak component in the upgraded MSX 140 version of the Ficht EMM.
    Last edited by K447; 10-30-2016 at 10:12 AM.

  3. #3
    martincom's Avatar
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    Welcome! You've obviously done your home work based on the tests and troubleshooting you've performed. So far, all your measurements appear normal. Inspecting the mating 12-pin receptacle on the EMM, how does it appear? Any signs of being hot?

    A few other things I would check:

    1. While cranking the engine with sparkplugs in and all electrical connectors mated, what is the voltage on the white/red wire that feeds power to the fuel injectors? Typically, the easiest place to access the white/red wire is at the diagnostic 4-pin connector near the EMM. It'll be a single jumper wire that just makes a loop to connect two pins of that connector. You need to keep this connected, so you may need to utilize a needle or similar item to reach in along the wire into the connector. I utilize a dental probe. This voltage should be near 21 volts DC while cranking and 45 volts while running.
    2. Disconnect the throttle position center (TPC) and attempt to start. If it does, it should just idle.
    3. You can disconnect the intake air and exhaust temperature sensors and substitute them with 1000 ohm resistors.

    We're kind of grasping at straws with #2 & 3, but they're cheap tests. Even if all these tests appear normal, you could still have an EMM issue. The EMM has two sections (circuit boards) that are NOT interconnected internally. The 40 pin connector connects to the control board. The two smaller connector connect to the power board. The best method to test an EMM is to swap it out. If you have access to an EMM from a two cylinder machine, you can swap out the power portion. You cannot swap out the control portion with an EMM from a 2-cylinder machine. Also, if you swap out the control section and it runs, keep your testing brief as the fuel injector flow parameters (coefficients) are programmed into the EMM. You've probably noted the warning label affixed to the air box that cautions in this regard.


    If you have heat damage to the 12-pin connector, it is probably indicative of an EMM failure or a poor connection. Inspect the pins in both the EMM and the connector for corrosion, deformation, or damage to the plating. replacement harness connectors are available online. Amazon offers kits which are pretty affordable verses purchasing pins & shells from distributors, such as Waytek Wire, due to the minimum order quantities. I believe they also pin extraction tool.

  4. #4
    CliffsidePM's Avatar
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    Welcome, Ovaboost. Update your profile on your location. Someone close may have an EMM or other parts you could try in your trouble shooting efforts.

  5. #5

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    Thank you all for welcoming me into your group and for taking the time to help me out .. its much appreciated. .here is a pic of the 12 pin plug
    hClick image for larger version. 

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  6. #6

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    Pic of the 12 pin plug.. note the melted plastic around the bottom of the no 4 and 11 pins .. no11 pin looks a bit discoloured as its burnt..
    Click image for larger version. 

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  7. #7
    Moderator HiPeRcO's Avatar
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    That plug looks bad. How do the pins on the EMM look?

    Edit: Yep, EMM pins show stress too.

  8. #8

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    Pulled the top cover of the EMM .. someone has obviously had a go at it at some stage , lol ... have a look at the attemt of the soldering on the s4 post.. looks to me like the solder is touching the s3 post as well !!??... to me the s1, f2 and s3 look like they dont have any solder on them , i thought they might have come of when i removed the gel but i cant see any traces of solder in there..Click image for larger version. 

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  9. #9
    Click avatar for tech links/info K447's Avatar
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    I would say the S4 solder had melted due to high pin temperatures and oozed into the gel material. If you peeled the original gel away from that area then I doubt it was ever repaired previously.

    Clean up the EMM connector pins (on the outside of the EMM) as best you can. Use gentle mechanical cleaning and electronics contact cleaner spray. Be sure the cleaner spray is plastic compatible. Try not to scrape up the gold coating on the pins. Use a bit of nylon scrubbie or tiny toothbrush to clean the contacts, not steel wool.

    Resolder the EMM pin board contacts. Pray that the board itself is not damaged on the underside. I used traditional 63/37 tin/lead solder with internal flux core (actually my favorite is Multicore).



    For the burned wire harness connector, replace all the burned pin sockets with new. Do not reuse the heat damaged metal parts. You can buy replacement Deutsch plastic shell and metal contacts online.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10

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    Cheers K447 ... i could be wrong but a few things i noticed about the EMM are making me think someone has had it apart. .. the plastic lid has a crack in it and was stuck to the gel when i tried to pull it off the EMM. . There is a foam type gasket that goes around the edge under the cover , it was kinked in a couple of spots and not sitting arount the edge where it ment to . The gell doesn't have a smooth and original finish like on the other side of the EMM , its lumpy and thick in some places and thinn and bearly covers the board in others.. and there is that solder on S4 which to me looks like it was poorly redone..anyways so far ive repaced the suspect pin sockets and cleaned up the plug and the EMM pins .. im not confident in soldering the Emm contacts so i might take it to my local electronic repair guy for that .. fingers crossed as far as any other damage caused.. again thank you all for your advice and ill keep you posted with the outcome..
    One thing i forgot to mention i also tested the injector voltage on the white red wire and i got 17.2 volts while cranking..
    Last edited by Ovaboost; 11-06-2016 at 05:07 PM.

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