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  1. #1

    LR-503 Module Complete Removal

    Hi all,
    I have read through all of the information about routing out the LR-503 start stop modules but I am curious if this module is actually required to be hooked up?
    I have two 1200 Di motors, one spare, powering a 13' inboard jet boat. I just had one blow the rear cylinder and am in the process of swapping in the other one, which is new to me and was already taken from the ski when I got it. It did not come with a start stop module. I am trying to make any future engine swaps once the first one is rebuilt a quick and easy job. The issue is the first one is an 01 and the 2nd is an 02. The old one has the start/stop mod routed out as it went bad. To save me from having to pull it from the electrical box and redo plugs, is there a way for it to not be used at all?

    I do not need or want start stop on the same button.
    I do not need or use the 12v power only on when engine is on.
    I also do not need or want the MFI Lockout to the starter solenoid.

    All I want is the starter to spin when I push the start button and the engine to shut off when I push the kill button.

    Any help would be greatly appreciated.

    Thanks,
    Riley


  2. #2
    Moderator HiPeRcO's Avatar
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    Welcome to Greenhulk! Sounds to me like you can indeed bypass/eliminate the LR503. The kill input to the EMM needs to be connected to ground by a kill switch. This can be wired in parallel to the lanyard switch (assuming you even have one, it would be a good idea to add one if you don't). One risk though is that if you press the start button while the engine is running, the starter will engage, likely resulting in damage to the flywheel teeth.

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  4. #3
    Yes, I have lanyard as well as a separate kill and a start button off to the side. Its not something I would accidentally touch while the motor is running. Could you help clue me in on what wires need to go where at the plug going to the LR module? I am assuming I can cap the yellow RPM signal, Orange 12v power.. Do I still connect the black/white and purple/white as you do when routing it out for testing purposes? Is the kill input to the EMM the black/yellow wire?

    Thanks for the help

  5. #4
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by HiPeRcO View Post
    ... you can indeed bypass/eliminate the LR503.

    The kill input to the EMM needs to be connected to ground by a kill switch. This can be wired in parallel to the lanyard switch (assuming you even have one, it would be a good idea to add one if you don't).

    One risk though is that if you press the start button while the engine is running, the starter will engage, likely resulting in damage to the flywheel teeth.
    Polaris did have watercraft models with no interlock between the Start button and the starter cranking the engine. So it was possible to engage the starter with a running engine. Makes a bad sound when you do that but most of the time the flywheel teeth and the Bendix seem to survive well enough.

    No problem with simplifying the start and stop button wiring to separate buttons. This was the factory configuration prior to 2000 on all models. The LR-50x module is not at all critical in your jet boat configuration.

    I agree that there should be a lanyard kill switch in addition to a stop button. Just wire the switches in parallel, one side of each switch connects to engine ground (black wire) and the yellow/black ignition kill wire goes to the other side of both switches.

    Start button goes from fused (circuit breaker) battery positive to the yellow/red solenoid wire. Other side of solenoid coil connects to engine ground (via a key switch if you want a tiny bit of kids/dummies/theft protection).

    Note that the external solenoids used by Polaris are polarity sensitive. There is a diode inside, wired across the coil. The diode is in there to limit unwanted electrical spikes that can cause the CDI to shut down unexpectedly. If you hook up the solenoid coil backwards the first time you press start it will blow the diode. The solenoid might still ‘work’ to start the engine but the pulse protection is gone.

    Also, if the start solenoid you have is the original from the Polaris factory, these are known to fail due to internal corrosion. Failure can result in the starter motor cranking continuously until something melts or breaks. Replace the original solenoid with an updated version. There is a Seadoo part number that is a direct replacement. Part number can be found via my signature link.

  6. #5
    Appreciate the help!
    Boat is already wired up so I will go through it tonight to figure out what I will need to change to make this work.
    Starter solenoid is already swapped.
    I have been lurking quite a bit here learning/doing what needs to be done to these engines. I really appreciate all the info here!

    Riley

  7. #6
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by rileypeck View Post
    Appreciate the help!
    Boat is already wired up so I will go through it tonight to figure out what I will need to change to make this work.
    Starter solenoid is already swapped.
    I have been lurking quite a bit here learning/doing what needs to be done to these engines. I really appreciate all the info here!

    Riley
    So, post up some good photos! We like pictures.

    This is a Ficht fuel injected engine, correct?

    Are you using the OEM fuel pump system?
    Have you reinforced the fuel pressure regulator inside the fuel pump body?

    You have the wiring diagrams, I presume.

  8. #7
    I will get some pictures together for your viewing enjoyment.
    Pump is OEM Re-enforced. I will be installing a fuel pump reman kit soon, I am pretty sure my last one burnt down due to a failing fuel pump.
    Do the fuel pressure regulators ever fail? I did the NPT thread fix and I popped the fuel pump body out to check so I know it didn't come off but that rear piston burnt just like it would if the thing fell off.
    It is a ficht engine.

    One awesome thing about working on this in a boat is everything on it is super easy to access! I had the motors swapped, shimmed and bolted down in about an hour. The electrical changes between 01 and 02 are hanging me up though!

  9. #8
    Click avatar for tech links/info K447's Avatar
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    What are you transferring electrically that would cause trouble? No need to swap wire harnesses, just install the new engine & injectors with the old harness, plug all the connectors back in, and plug in the matching 2002 EMM.

    The 2002 EMM plugs in the same way as the 2001.

    The fuel injectors are the same connections.

    You had it running with the old Ficht engine, correct?

  10. #9
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by rileypeck View Post
    ... I will be installing a fuel pump reman kit soon ...
    Be aware that the OEM Polaris Ficht fuel pump has a fairly low amp draw.

    We have found that many of the ‘replacement’ FICHT fuel pumps demand too much electric current. The EMM cannot cope with the excess amps for the new fuel pump and burns out the driver transistor inside the EMM.

    I think there is one aftermarket fuel pump that may have a low enough amp draw to work ok. Others on here should have more details.

  11. #10
    Yes I had it running, ran great for 3 trips then the rear piston failed. The new motor came with the harness all hooked up ready to go. It's different enough though I'm having to extend some plugins and route out the lr mod.

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