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  1. #1

    2001 Polaris Virage TXi 1200 - Low injector voltage, I've replaced everything.

    I'm working on a 2001 Polaris Virage TXi 1200 and I'm at a loss. It originally came in with a bad fuel pump, which was replaced and now works. However, it still wouldn't start afterwards. It wasn't getting proper voltage or ohm readings from the stator, so I tore it down and found that the stator had taken in water and the flywheel magnets had also fallen off. I ordered a brand new stator and flywheel and installed them. The new stator ohms out and reads correctly.

    However, it still wouldn't start, so I checked the injector voltage, and found that it is only getting 7-10 volts while cranking. I can unplug the diagnostic connector near the EMM and get ~14-16 volts, but then I lose spark. I can also pour a small amount of fuel in the throttle bodies and it will fire right up and run, and the injector voltage is fine while revved up, but it doesn't like to idle (voltage drops to ~25-30). I've tried everything I can think of, and finally got to the point where I just started throwing parts at it and still haven't made any progress.
    Here is a list of everything that has been done to the machine so far:

    No codes in DigitalWrench.
    New fuel pump - Fuel pressure is correct.
    New stator - Ohm readings and output are correct.
    New flywheel - Old magnets had moved.
    New Polaris EMM (1) - No change, voltage still jumps up when diag. connector is unplugged.
    New Polaris EMM (2) - No change, voltage still jumps up when diag. connector is unplugged.
    New Start/Stop module - Also did the bypass on the old one, no change in symptoms.
    New complete wiring harness - Tried with both original EMM and new EMM, no change in symptoms.
    New capactor - Tried on both old and new harness, no change in symptoms. Also, drops voltage steadily on old and new cap.
    New CPS - No change in symptoms, old one Ohm'd out fine and showed output on DW.
    New battery - Tried 2 different new batteries with full charges, no change.
    Cleaned and sealed all grounds and main cables, along with all splice blocks (were already perfectly clean).
    Checked entire wiring harness for cross-shorts, bad grounds, or voltage drops, checks out fine.
    Tried unplugging individual/all coils, injectors, and sensors to eliminate one being the problem.
    Will not fire up with TPS unplugged, but will run with added fuel when plugged in. Shows no fluctuations in DW. Have not tried to replace it yet.
    Tried unplugging and jumping the connector for the Multi Display.
    Tried unplugging and jumping the tether switch.
    Tried unplugging bilge pump and holding button while attempting to start.
    Both fuses are good.
    Compression is fine.
    Temperature sensor Ohms out fine.
    All sensors are in proper ranges in DW.

    None of this has made any change in symptoms. Both DFI and Polaris HQ have no ideas.

    I know there is more that I've tried, but that is all I can remember at the moment. Any ideas?


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

    I do not understand why you have not yet changed the TPS, despite the TPS being a well known failure point and easy to replace.

    When you swapped in the other two EMM, where did they come from? Are these known good/tested EMM?

    Have you verified that the EMM is indeed correct for this model engine? A two cylinder EMM will not run properly in a three cylinder engine.

    When the new flywheel was installed, did you use a new or Polaris OEM woodruff key? I am wondering if the flywheel shifted/sheared the key, and engine timing is now incorrect by a few degrees.

    Have you checked the crank shaft index? If it has twisted out of time for CEN/PTO then it won't run well.

    What is the fuel pressure? If you clamp the return hose between Schrader valve tee and fuel tank return fitting, what does the fuel pressure increase to?

    Not that it should affect injector voltage directly, but have you verified that the correct wire colors are connected to each cylinder ignition coil and injector? It is easy to swap adjacent connections and not notice.

  3. #3
    Quote Originally Posted by K447 View Post
    Welcome

    I do not understand why you have not yet changed the TPS, despite the TPS being a well known failure point and easy to replace.

    Mostly because it seems to test fine. It shows no dead spots or fluctuations in DigitalWrench, and it is in spec, I've checked several times. When unplugged, it will not allow the machine to fire up with fuel poured down the throttle bodies. When plugged in, it will allow it to start with fuel poured down the throttle bodies.

    When you swapped in the other two EMM, where did they come from? Are these known good/tested EMM?

    Brand new Polaris OEM EMM's. I've also tried to start the machine before flashing the EMM's to the machine (they come 'pre-programmed'), and after being flashed. Still no changes.

    Have you verified that the EMM is indeed correct for this model engine? A two cylinder EMM will not run properly in a three cylinder engine.

    Yes, they are the correct EMM for the machine. It will start and run on all three cylinders with any of the three EMM's once fuel is poured down the throttle bodies.

    When the new flywheel was installed, did you use a new or Polaris OEM woodruff key? I am wondering if the flywheel shifted/sheared the key, and engine timing is now incorrect by a few degrees.

    Polaris OEM key.

    Have you checked the crank shaft index? If it has twisted out of time for CEN/PTO then it won't run well.

    No, the engine has not been torn down yet. The main problem is the injectors aren't getting enough voltage to pop open to get the engine to start in the first place. It does run fine once it does start (when I add fuel), so I don't have any reason to suspect the crank has twisted.


    What is the fuel pressure? If you clamp the return hose between Schrader valve tee and fuel tank return fitting, what does the fuel pressure increase to?

    I believe it was 20-25 PSI. I will re-check and also try pinching the return line in the morning.

    Not that it should affect injector voltage directly, but have you verified that the correct wire colors are connected to each cylinder ignition coil and injector? It is easy to swap adjacent connections and not notice.

    Yes, I have verified that all the wires are in their correct locations.
    Answered above.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Correct spark plugs installed? Just want to be sure something basic is not being overlooked.

    The wire harness swap is the one that surprises me, that it made no difference.

    So the electrical components that have NOT been swapped are;

    Fuel injectors
    Exhaust temp sensor
    Intake air temp sensor (any damage from FA cover?)
    TPS
    Ignition coils
    High voltage plug wires
    Spark plugs

    Anything else electrical that is still original?

    When you measure White/Red wire voltage with diagnostic loop connector unplugged, where are you testing the voltage?

    With stator 8-pin harness connector unplugged, are you getting the correct AC voltage on every wire pair?

  5. #5
    Quote Originally Posted by K447 View Post
    Correct spark plugs installed? Just want to be sure something basic is not being overlooked.

    Yes, correct plugs are installed, and they are new as well.

    The wire harness swap is the one that surprises me, that it made no difference.

    It surprised me too, as it was the latest thing I've tried.

    So the electrical components that have NOT been swapped are;

    Fuel injectors Have not been swapped, but I've tried unplugging them one at a time and all at once, no change. I can also make each one fire individually with DW.
    Exhaust temp sensor Hasn't been swapped, but does Ohm out correctly, and shows a proper reading in DW.
    Intake air temp sensor (any damage from FA cover?) Hasn't been swapped, but I will inspect it closer for any signs of damage tomorrow.
    TPS Hasn't been swapped, but does work fine according to DW, and does affect runability when unplugged.
    Ignition coils Haven't been swapped, but have also tried unplugging them one at a time and all at once, with no change. I can also make each one spark with DW. They Ohm out fine.
    High voltage plug wires Haven't been swapped, but Ohm out fine and have no signs of damage.
    Spark plugs Spark plugs are new and the correct plug.

    Anything else electrical that is still original?

    Not that I can think of. I've even changed out the starter solenoid, as well.

    When you measure White/Red wire voltage with diagnostic loop connector unplugged, where are you testing the voltage?

    Right off the injector with a Polaris injector adapter harness. I've tried this at each injector with no change.

    With stator 8-pin harness connector unplugged, are you getting the correct AC voltage on every wire pair?
    Yes, last time I checked. I can check again in the morning. The stator does Ohm out fine.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Nick_R_23 View Post
    Quote Originally Posted by K447
    When you measure White/Red wire voltage with diagnostic loop connector unplugged, where are you testing the voltage?
    Right off the injector with a Polaris injector adapter harness. I've tried this at each injector with no change.

    ...
    Going from memory here, my (incorrect, see edit below) understanding is the loopback connector isolates the section of the wire harness that actually powers the injectors. If I am correct, you cannot measure at the injectors to observe the output of the EMM power section with the loopback connector unplugged. You would need to measure the White/Red wire right at the loopback connector.

    Edit: Too tired, making errors.
    Just checked the wiring diagrams. The loopback isolates the EMM operational section from the 45 volt power source. You can measure White/Red voltage, with loopback unplugged, at the loopback connector side that has a single wire present.

    The EMM power section outputs the 45 volt (and 12 volt) power on the 8-pin connector. The 45 volt power feeds out to the capacitor, injectors, and also feeds back into the EMM on the large 40-pin connector (via the loopback connector).

    This is why you need to install a Service Power jumper on the 8-pin connector to use DW with the engine off. That jumper simply pumps 12 volt battery power onto the '45 volt' side, which is enough for the EMM to be awake, but it is not enough voltage to actually fire the fuel injectors.

    Note that the White/Red wire that feeds each injector is a common power feed, all those wires are connected together. If you have the Digital Wrench diagnostics harness hooked into the EMM, make sure the DW harness itself does not have a bad wire or dirty/broken pin connection. If you only have one of these things, make sure it isn't damaged or misleading you.
    Last edited by K447; 05-18-2013 at 07:21 AM.

  7. #7
    Quote Originally Posted by K447 View Post
    Just checked the wiring diagrams. The loopback does indeed isolate the injectors from the 45 volt power source. You would need to measure White/Red voltage, with loopback unplugged, at the loopback connector side that has multiple wires present.
    I'll try that in the morning, thanks! However, if unplugging the loopback connector isolates the injectors from the +45V source, then why is my voltage at the injectors jumping up when the loopback is unplugged? Shouldn't I get no voltage, then?

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Nick_R_23 View Post
    Quote Originally Posted by K447 View Post
    Just checked the wiring diagrams. The loopback does indeed isolate the injectors from the 45 volt power source. You would need to measure White/Red voltage, with loopback unplugged, at the loopback connector side that has multiple wires present.
    I'll try that in the morning, thanks! However, if unplugging the loopback connector isolates the injectors from the +45V source, then why is my voltage at the injectors jumping up when the loopback is unplugged? Shouldn't I get no voltage, then?
    I corrected (I think) my post.

  9. #9
    Quote Originally Posted by K447 View Post
    ]I corrected (I think) my post.
    That makes more sense. Just to clarify, the loopback connector being plugged in and reading 7-10 volts, and the connector being unplugged and reading 14-16 volts (both readings taken at the injectors), are without the DigitalWrench in the system. The ski is completely powered by itself.

    I do have the 8 pin jumper installed when using DW, and the cable is working, also.

    So, it looks like I need to test for my +20 volts at cranking, at the single wire side of the loopback connector, is that correct?

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Nick_R_23 View Post
    Quote Originally Posted by K447 View Post
    ]I corrected (I think) my post.
    That makes more sense. Just to clarify, the loopback connector being plugged in and reading 7-10 volts, and the connector being unplugged and reading 14-16 volts (both readings taken at the injectors), are without the DigitalWrench in the system. The ski is completely powered by itself.

    I do have the 8 pin jumper installed when using DW, and the cable is working, also.

    So, it looks like I need to test for my +20 volts at cranking, at the single wire side of the loopback connector, is that correct?
    It would seem this is the core problem, low voltage on the 45 volt circuit. There are only a handful of components involved;

    • Flywheel magnets
    • Magneto stator
    • Stator harness to EMM 12-pin connector
    • EMM power section, which rectifies the AC from the stator and regulates the 8-pin output (both battery charging and injector voltage outputs)
    • White/Red and Black/Ground harness wires related to injector circuit, loopback plug
    • Wire splice connectors in White/Red and Black/Ground circuits
    • Large capacitor connected to White/Red and Black
    • EMM itself drawing from White/Red on 40-pin connector

    Working from first principles;

    Confirm correct AC voltages on each wire pair of 12-pin connector while cranking. Monitor battery voltage sag while cranking and confirm proper cranking RPM.

    AC voltages good?
    Connect 12-pin, disconnect 8-pin at EMM. Touch meter probe to either pin 1 or pin 8 (where White/Red normally connects). Crank and record voltage output. Note, the capacitor is isolated from EMM so voltage reading and post crank sag will be different.

    Reconnect 8-pin to EMM. Disconnect loopback connector and connect meter to White/Red wire adjacent to other wires. Record voltage while cranking, and observe post crank sag rate.

    Note: You said you cleaned and verified all Black ground connections to/at the physical engine. And have a new/replacement wire harness installed. Nevertheless, it might be useful to ohm check from the battery negative post (battery positive disconnected) to each important Black wire connector in the wire harness. All connections should be under 1.0 ohms to battery negative post. As should the engine case itself, of course.

    EMM 8-pin Black on pins 3-4-5-6.
    Capacitor Black terminal.
    EMM 40-pin harness connector 1-11-20-21-27-30-31-37
    Wire harness ground at ignition MAG ignition coil mounting bolt

    Note: I don't like the factory ground bolt arrangement for the ignition coils on the red Ficht engines. I prefer to remove the coil, relocate the fiber washer to between the coil body and the coil's metal ground tab.
    Clean the coil grounding tab, the engine mounting boss surface where the tab will contact, run a tap into the thread holes, clean the bolt threads. Now there will be two electrical paths for coil ground; via the bolt threads, and via the coil ground tab pressed against the engine itself.
    I also use very little thread locker on the bolt that actually provides the ground (I use none during this sort of testing). The other bolt on each ignition is just providing mechanical support, not electrical ground.

    I do this for all three ignition coils, even though only the MAG coil front bolt is also proving wire harness ground.
    Last edited by K447; 05-18-2013 at 07:59 AM.

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