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What is stopping the fuel pump

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I'm working on a 2003 Mitsubishi Diamante 3.5l drove home the other night and parked. when i went to start it the next day it just cranked over and over. i could not hear the fuel pump running so pulled it out and bench tested it, it was fine. i received 2 trouble codes a P0340 and a P0335 camshaft sensor and crank sensor. Any ideas would be greatly appreciated 

Verified Answer
  • If codes P0335 and P0340 CKP and CMP signals were not detected for 2 seconds the cam and crank sensor circuit may be shutting down the fuel due to a non-spark condition.

    Check the electrical circuit for something the 2 sensors have in common.



    5v VREF to the sensor

    MFI relay

    Open or shorted signal circuit

    Sensor power circuit is open

    Ground circuit is open

  • I do not know if you already fixed the problem, but I had the same issue with a v6 gallant. Fuel pump as well as p0335/p0340

    The reason for the both the fuel pump not working and the error codes was a open circuit inside the PCM.  The PCM controls the coil inside the fuel pump relay. It will momentarily do this when you initially turn the key to the on position then provide a constant connection after you start the engine.

    The relay has four connections. There are two 12 volts inputs from the fuse box, one is 12 volts output to the fuel pump, and the last one is wired to the PCM. The one you want to test is the wire going to the PCM.

    Using a digital volt meter in the volts settings and one lead on ground, look for zero volts at the times it should be on. About 12 to 14 volts means one of two things, open circuit or measuring the source voltage.

    (Note: Once you locate your relay, you will not be able to identify the connections by looking at them. You can look at the underside of the relay and see that there are identifiers like coil, com, and N/O. Also, realize that while looking on the bottom of relay, that the actual connections are inversed. Left is right and so forth.)

              N/O is going to the fuel pump

              Com and Coil(There two)are going to 12 volts at the fuse box

              Coil(other one) goes to the PCM

    The shortcut to making the fuel pump run is to jump one of the input 12 volt connections to the output connected to the fuel pump. N/O to COM.

    If you find that the PCM does not short to ground when it should to make the fuel pump relay turn on, then replace it. Recommend a used one but for piece of mind refurbished one would be best.

All Replies
  • If codes P0335 and P0340 CKP and CMP signals were not detected for 2 seconds the cam and crank sensor circuit may be shutting down the fuel due to a non-spark condition.

    Check the electrical circuit for something the 2 sensors have in common.



    5v VREF to the sensor

    MFI relay

    Open or shorted signal circuit

    Sensor power circuit is open

    Ground circuit is open

  • I am getting spark at plugs i tried spraying starting fluid in intake and still no start. found 4 relays under dash in center which one is fuel pump relay?

  • http://i1186.photobucket.com/albums/z374/CengageChilton/83e867d1.png

    http://i1186.photobucket.com/albums/z374/CengageChilton/f358fcfd.png

    http://i1186.photobucket.com/albums/z374/CengageChilton/b4ecca9b.png

    http://i1186.photobucket.com/albums/z374/CengageChilton/0a30f286.png

     

     

  • I do not know if you already fixed the problem, but I had the same issue with a v6 gallant. Fuel pump as well as p0335/p0340

    The reason for the both the fuel pump not working and the error codes was a open circuit inside the PCM.  The PCM controls the coil inside the fuel pump relay. It will momentarily do this when you initially turn the key to the on position then provide a constant connection after you start the engine.

    The relay has four connections. There are two 12 volts inputs from the fuse box, one is 12 volts output to the fuel pump, and the last one is wired to the PCM. The one you want to test is the wire going to the PCM.

    Using a digital volt meter in the volts settings and one lead on ground, look for zero volts at the times it should be on. About 12 to 14 volts means one of two things, open circuit or measuring the source voltage.

    (Note: Once you locate your relay, you will not be able to identify the connections by looking at them. You can look at the underside of the relay and see that there are identifiers like coil, com, and N/O. Also, realize that while looking on the bottom of relay, that the actual connections are inversed. Left is right and so forth.)

              N/O is going to the fuel pump

              Com and Coil(There two)are going to 12 volts at the fuse box

              Coil(other one) goes to the PCM

    The shortcut to making the fuel pump run is to jump one of the input 12 volt connections to the output connected to the fuel pump. N/O to COM.

    If you find that the PCM does not short to ground when it should to make the fuel pump relay turn on, then replace it. Recommend a used one but for piece of mind refurbished one would be best.

  • Thanks Jlanstead!