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P3190 keeps returning.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Weroance, Jul 10, 2022.

  1. Weroance

    Weroance New Member

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    I got p3190
    removed and cleaned the throttle body and the MAF
    it ran for two days
    then p3190 again
    replaced the throttle body with a used one
    it ran ... for a day and then p3190
    its been sitting since.
    I'm about to run through the troubleshooting properly according to the manual. crankshaft sensor etc. but I am puzzled why my attempts have been temporarily effective.
     
    #1 Weroance, Jul 10, 2022
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    It may not have been "temporarily effective", but more "the ecu didn't quite see things were bad enough to set a code immediately".

    That code indicates that the Internal Combustion Engine didn't produce as much torque as the hybrid control computer (ecu) expected. A place to start looking would be in scan data for the Engine Control Module. Specifically at Short and Long Term Fuel Trims. (Short plus Long equals Total FT).

    The ECM takes input from various sensors on the ICE - esp RPM (crank sensor) & load (MAF sensor) and figures out how much fuel to inject. Fuel trim is an adaptive response to the Air Fuel sensor- which measures the air fuel mixture in the exhaust (ie, the results of combustion). Based on that signal, the ECM can add more fuel (+ fuel trim), or reduce fuel (- fuel trim).

    If everything works like it did when the car left the factory, fuel trims should stay near zero. If fuel pressure goes slightly low, the ECM would add fuel to try and compensate (+ FT). If injectors were leaking some, the ECM would reduce fuel (-FT).

    So monitoring fuel trim at different conditions (idle, accel, cruise) can give us some idea how close things are to factory spec- or not. If FT is off, then we can try to figure out if it is an input - sensor problem, fuel system, or engine.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jul 11, 2022
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  3. PriusCamper

    PriusCamper Senior Member

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    Any other symptoms? How many miles on your Prius? Have you replaced spark plugs yet? Usually done at 150K miles... Old plugs will give you a chance to see how things have been combusting in each cylinder of late.
     
    #3 PriusCamper, Jul 11, 2022
  4. Weroance

    Weroance New Member

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    I just performed a pressure test and I have zero fuel pressure so the pump is not turning on apparently. Engine was not running between code resets merely trying to start. I suppose I next check for voltage at the pump.
     
    #4 Weroance, Jul 13, 2022
  5. Weroance

    Weroance New Member

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    This is confusing. I probed the pins on the connector at the tank and have voltage to the pump during start. I also jumped the pump and it is whirring.
     
    #5 Weroance, Jul 13, 2022
  6. Weroance

    Weroance New Member

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    So this could be a bad pump (mechanically) or a blocked filter or pressure regulator? But ZERO fuel pressure? a leak? where to go next? drop the tank and bench test the pump?
     
    #6 Weroance, Jul 13, 2022
  7. Weroance

    Weroance New Member

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    I jumped the fuel pump again and popped the fuel tube afterward. some pressure was held. When I tested the voltage being sent to the fuel pump it read 13.4 v (my battery is at 12v)
     
    #7 Weroance, Jul 14, 2022
  8. Weroance

    Weroance New Member

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    DO I need the mini VCI cable to continue?
     
    #8 Weroance, Jul 14, 2022
  9. mr_guy_mann

    mr_guy_mann Senior Member

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    If the pump is getting power and making noise but no fuel pressure- any chance you're "just" out of gas?

    Posted via the PriusChat mobile app.
     
    #9 mr_guy_mann, Jul 15, 2022
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  10. Weroance

    Weroance New Member

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    Thanks for checking back. No its over 5 gallons. I was using a loaner fuel pressure guage and returned it before i thought of the jumped pump test. Anyway there was no pressure in the system when i removed the guage so im thinking its down to the relay or ecm.

    Each time this happens its like a switch. Really good performance and mpg and then bam nothing. No fuel apparently. Grabbed a relay to swap from the junk yard but have never tested either the correct way. Need some better tools. I want to jump the pump with a guage in line and test the relay. Will the vci cable help at all? Good instructions for testing the relay /supply/ecm?
     
    #10 Weroance, Jul 18, 2022
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    If you have Techstream installed and working (or an app and device such as ThinkDiag), then you can ask the ECM to turn the fuel pump relay on and perform testing on the fuel supply system.

    Testing procedures and wiring diagrams are in the service manual.

    Posted via the PriusChat mobile app.
     
    #11 mr_guy_mann, Jul 18, 2022
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    Ideally you would connect a pressure gauge to the fuel system so that you can safely monitor pressure and see if it drops when your symptom occurs.

    Also I would connect a multimeter (or a small 12V light) to the fuel pump wiring at the tank connector. That way you can monitor power supply to the pump at the same time as pressure on the gauge.

    If pressure drops but power stays steady, then something is bad inside the sealed fuel tank assembly. Time for a new one.

    If power goes away when pressure drops then you have to look upstream at the wiring, relays, ECM, etc.

    Posted via the PriusChat mobile app.
     
    #12 mr_guy_mann, Jul 18, 2022
  13. Weroance

    Weroance New Member

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    This problem is not presently intermittent. I found the troubleshooting guide for the ecm which is relevant to the fuel pump controls too.
     
    #13 Weroance, Jul 29, 2022
  14. Weroance

    Weroance New Member

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    * SOLVED *

    First I searched the manuals for ALL the troubleshooting guides regarding fuel pumps.
    Probed the pump power at the pump and found very low voltage.
    Probed the harness in the drivers side kick panel and had normal voltage.
    moved downstream to a connector in the hatch above the starting battery and battery cooling fan.
    Found it had been "repaired" by an idiot. It had gotten wet from the normal prius roof leak and corroded, so someone pulled the wires out of the plug and soldered the connection for the cooling fan but for the fuel pump the wires were wrapped around each other and held together with electrical tape.
    I soldered this connection and all is fine.
     
    #14 Weroance, Oct 26, 2022
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  15. mr_guy_mann

    mr_guy_mann Senior Member

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    #15 mr_guy_mann, Oct 27, 2022
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