fuel pressure regulator

Discussion in 'Engine, Fuel and Exhaust' started by nascar7613, Dec 28, 2011.

  1. nascar7613

    nascar7613 Active Member

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    2007 Softail Duece. Bike would start, stall, start, stall. Looked inside fuel tank and found that the fuel pressure regulator plastic housing had a broken tab. Replaced the housing but now the pressure regulator keeps pushing out of the housing slightly and the bike doesn't want to take gas and eventually stalls. I bent the tabs on the cover plate where the housing goes in as much as I could to try to hold the regulator in tighter, but it still pops out enough to cause a problem. Thanks in advance for any advise.

    Also, the code PO107 was set. It took several attempts to clear the code through the speedo. After clearing the code, the bike would run the same, and the code will come back.:wall
     
    Last edited by a moderator: Dec 28, 2011
  2. Hoople

    Hoople Account Removed

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    P0107 is Map sensor voltage is low or missing.
    I would 1st disconnect the connector at the map sensor and check to see if you have the +5 reference voltage between pins A & C. (on the harness side of the connector. A is +5 and C is ground) If you don't read +5, the pigtail probably has a broken wire under the rubber insulation.

    If you do read that +5 voltage, then turn off the key and check for continuity from the B terminal (center pin) of the map sensor to pin 25 of the ECM connector. You must read near zero ohms.

    My money is on a wire fracture in the pigtail at the map sensor or poor connection right at the sensor.
    This code will post regardless of fuel pressure. It must be repaired first.
     
  3. eleft36

    eleft36 Junior Member

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    Did you change the fuel filter and what is the fuel pressure?

    Al

    :USA
    :CONNECTICUT
     
  4. nascar7613

    nascar7613 Active Member

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    I am getting 2.2 volts at the connector to the sensor and also 2.2 volts coming out of the ECM. All of the wires show continuity between the ECM and the sensor.
     
  5. Hoople

    Hoople Account Removed

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    You need to supply more details. Supply wire color you are reading that value on. Saying you read "continuity" means nothing. Need to know the ohm value and meter scale range you are on. If your meter range was on 200K and your meter reads 0, you could have 200 ohms of resistance and never even know it. This is a very important (and could be costly) reading so just in case, here are the exact steps.

    Remove the connector (#80) going to the MAP sensor. The colors of the wires should be Red/White,, Violet/White & Black/White. Is that what you have?
    If yes, using a quality meter with the ignition ON, measure the DC voltage between the Red/White and the Black/White. Now take a reading between the Red/white and the Negative POST of the battery. What reading do you measure. It should be ~ 5.0v DC. If you read 2.20 volts once again, perform the following =>

    Turn off ignition. Disconnect the TPS connector (#88) from the throttle position sensor. Disconnect the VSS (#65) from the vehicle speed sensor. All 3 connectors (80,88,65) should now be disconnected at this time. Once again, using a quality meter with the ignition ON, measure the DC voltage between the Red/White and the negative POST of the battery.

    Do you still read 2.2 volts DC.
     
  6. nascar7613

    nascar7613 Active Member

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    Sorry for the delay. The wires are as you described, red&white, Violet&white and black&white. I checked the resistance with a quality dvom which has proven to be reliable for a long time. I also did what you suggested by disconnecting the tps and the vss along with the map sensor and still get the 2.2 volt reading going from the red&white wire to the negative post on the battery. I also noticed that when I had my twin scan connected to the bike the throttle position guage in the software only goes to 45% when I have the throttle at 100%. Thanks for your advise.
     
  7. Hoople

    Hoople Account Removed

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    I assume that the bike is in stock form (not using a ThunderMax ECM), with no added devices (Power commander etc) hooked between the stock ECM and the ECM harness. I am assuming you have a standard HD Delphi factory ECM, with no add on fueler devices.

    If so, the next thing to do would be to leave the 3 connectors (80,88,65) disconnected and also unplug the 36 pin ECM connector right at the ECM.
    Inspect the pin side (the ECM) connector for any corrosion or oxidation. Also inspect the female (wire harness) side 36 receptacle connector.

    Now pull the Maxi fuse and place your multimeter in the 20Meg ohm scale and measure the value between the Red/White wire of the MAP sensor cable and FRAME Ground. You must read Infinity. If you read something other than Infinity, the Red/White reference supply wire is leaking current to ground and is pulling down the 5 volt ECM reference supply.

    But if you do read infinity (a value greater than 20 meg ohms), it sure is not looking good for your ECM.

    The reason I say that is because according to my 2007 Softail schematics, Pin 14 of the ECM is the 5 volt reference supply. It only supplies power to 3 input devices. They are the Map sensor, VSS sensor and TPS sensor. We disconnected all three sensors (in case 1 sensor was shorted) and the voltage still measured low. So we tested the 5 volt supply wire (Red/White) for leakage to ground. If we find no leakage, it doesn't leave us much except an ECM with a bad 5 volt reference power supply. By the way, Pin 26 of the ECM is ground for the +5 volt reference (which is the Black/white wire on all 3 sensors but it also ties to frame ground).

    What you said about the 45% electrical throttle showing at a 100% mechanical throttle, also supports the theory of a bad reference voltage.

    I always hate to call out an ECM as being bad because they are expensive. If you happen to have schematics, double check my work just to be sure.
     
  8. bobwire

    bobwire Active Member

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    hoop, i'm dumb as a mud turtle, but i almost understood you, good job..........bw
     
  9. R_W_B

    R_W_B Senior Member

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    Absolutely fantastic information here. Nascar I hope you get it ironed out without having to buy a new ECM.

    Hoople do you get all your schematics here on the forum or do you have your own database collection? Just curious, I promise not to ask you to burn me a DVD.
     
  10. nascar7613

    nascar7613 Active Member

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    The bike is all stock. I ran all the test you suggested a second time and this time when I unplugged the vss, the voltage from the red&white wire on the MAP sensor to battery ground came up to 5.0 volts. Plugged everything back in and then unplugged everything again and still got the 5.0 volts by unplugging the vss. It seems that would point to a bad vss drawing voltage away from the other sensors. The test where I unplugged the ecm and took out the maxifuse was infinity. Thanks again for your help. It's awesome that someone with your knowledge is on here willing to help.

    Also, when I pulled out the vss, one of the prongs on the sensor, the one that connects to the black wire, was discolored while the other two prongs were shiny, but all three connectors on the plug itself looked good.
     
    Last edited by a moderator: Dec 30, 2011