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  1. #1

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    MSX RPM locked at 3500 no codes

    I have a 2003 MSX 140. It is very low hours EMM says 9 hrs via digital wrench. I think it may have been changed. The MFD says 25hrs. Guy I bought it from said 25. I have been through this thing in every possible way. The gist is that I have what appears to be in the S.L.O.W. mode. Though no indications from the dash or from Digital Wrench. I sent the EMM to Harris and had him rework it and same affect so I sent back to him for double check and I performs perfectly on his ski. I have replace the plugs with correct plug(NGK PZFR6H). The fuel pump is putting out 23.4 lbs pressure after returning to the Polaris in tank regulator.

    Right now starting from cold It wont start. If I hit it with a small amount of starter fluid it will fire up immediately and run fine up to 3500 rpm. It will then start fine after its warm.

    According to digital wrench everything appears to be within specified range. The 4 items that are usually suspect for SLOW mode:
    EMM temp
    Water temp
    alternator over voltage
    reverse limit switch
    None of these are present. Digital Wrench says "no codes set". I did go ahead and do the reset anyway and no change.
    Anyone have any ideas that might help get to the bottom of this?

    Other things done.

    I replaced the TPS with new and same effect.
    Did fuel pump fix for the regulator using the threaded nipple approach suggested on K's site.
    Removed inline Kaw regulator I previously installed. (Was reading high at 37)
    Removed intake to look at reeds and seals.

    The one thing I have tried to avoid is taking my EMM from my second MSX 140 to see if trouble remains. We use the other ski so much since we live on the lake. If it is the EMM then it doesn't make since why it works well for Harris. If it has the same issue than what would I need to do next? What kind of things would injectors cause if some had put the wrong set or not calibrated them to the EMM? Would DW alert me to that? There is a section in digital wrench that give all the detail on the injectors. Voltages to injectors are right according to the documentation.
    Last edited by raydmo; 09-16-2016 at 08:05 PM. Reason: spelling


  2. #2
    martincom's Avatar
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    What does it do if you unplug the TPS and start it? The hard starting when cold is unusual for DI. The EMM is not that difficult to remove on the MSX. I'd swap the other one, it would be a huge step in the process of elimination. Next, I'd take a look at the CPS. Check for broken pins and corroded connectors while you're at it. When you have the CPS out, look for water/debris in the flywheel housing. Does the display RPM appear correct and not erratic?

    Each injector has a S/N on it's label. You can compare that to the injector S/Ns in DW to verify you have or have not the injectors programmed into DW as well as if they are installed on the correct cylinder. Though even if they're mismatched, I don't believe that is your issue.

    You can replace the temp sensors with 1000 ohm resistors for testing. 1000 ohms is the value they would be for a temp of 70F. You'd think a bad temp sensor would show up in DW, but when they're mechanically intermittent, they don't always.

  3. #3
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by raydmo View Post
    I have a 2003 MSX 140...

    Right now starting from cold It wont start. If I hit it with a small amount of starter fluid it will fire up immediately and run fine up to 3500 rpm. It will then start fine after its warm.

    ...
    What voltages are you measuring for the white/red wire? All injectors plugged in, voltage should be more than 20 volts while the engine is cranking? Is it?
    Last edited by K447; 09-17-2016 at 07:24 AM.

  4. #4
    Kosh's Avatar
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    You sure it's not in reverse?
    no codes for that if it's just a defective sswitch

  5. #5

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    Quote Originally Posted by Kosh View Post
    You sure it's not in reverse?
    no codes for that if it's just a defective sswitch
    just unplug it for testing

  6. #6

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    As a follow up to my post I thought I would tell everyone what I found. Pin 40 on the EMM connector supplies the ground to the fuel pump. The positive side of the pump has a constant 12Vdc there. The EMM supplies the ground to the pump. What I discovered was the Pump was never starting at 12Vdc it was starting around 8.5Vdc and over a period of time would drop to 2.5Vdc. The voltage drop caused a limitation to 3500rpm which was very ironic that it caused th engine to lock in at 3500rpm. When I supplied a direct chassis ground to the pump it ran full speed and the fuel pressure remained at 27psi. Prior to the ground the pump would start at 27psi but taper off over time which would cause the engine to only reach 3500rpm. This limitation did not create what seemed like a typical fuel starvation to the engine, it sounded like it was rev limited electronically. I worked with Harris on the EMM and after his testing and proving the EMM good helped me know what supplies the ground to the EMM. Ultimately it was an issue with ground supplied to the EMM. I ran it this weekend and it flies like my other MSX140. Now on the MSX 150 I just purchased.

  7. #7
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by raydmo View Post
    ... after his testing and proving the EMM good helped me know what supplies the ground to the EMM. Ultimately it was an issue with ground supplied to the EMM.

    I ran it this weekend and it flies like my other MSX140. ...
    What exactly was the problem location and what did you do to fix it?

  8. #8
    Moderator HiPeRcO's Avatar
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    You're lucky you didn't burn down the motor, it was probably running extremely lean.

    Looking forward to hearing about your 150

  9. #9

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    Well I had never run it on the water. I purchased it with the issue I was working on which by the way is why they sold it. So it had never been run much. You are right I am a lucky guy.

  10. #10

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    K this ended up being unique. Trying to determine which analog input ground was feeding the EMM...as there are several made for a wire chasing frenzy I was just personally not willing to make. I had spent so many hours chasing this down I was ready to move on. Everything else on the ski works perfectly. At the same time I moved to an external fuel pump and added an adjustable inline fuel regulator with view-able gauge. How I solved was not in a purest way. I fixed it by adding a waterproof lighted stainless push button on off switch for the fuel pump that simply adds a chassis ground. See attached. I added it on the console just above and to the left of the glove box. It made for a simple fix. Somewhere in the wiring harness is a high joint in a ground lead of which there are about five that go the EMM. Had there been a schematic of the EMM to tell where PIN 40 receives its analog ground would have been helpful. Harris and talked it out. Another more energetic person might have taken the necessary time to chase it down further. Several months of tinkering with this made me less open to further chasing.
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