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And so it begins...

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  • And so it begins...

    Screenshot_20200730-181330_resized.png Truck has been running great....until today. Today was hot. Like 117 degrees kinda hot. After a 30 mile drive home from work the truck didn't want to restart. Had to crank it awhile and finally gave it some gas pedal to get it to fire. Once running it seemed to idle a little rough, like it was loaded up. The display showed the afr was rich and the long FT kept flashing red. It seemed to clear once driving but the next stop resulted in the same scenario.

    Once home I let it sit for a couple hours and tried to start it. The engine temp was down to 184, so it was trying to start in closed loop. She just cranked over again. I didn't try to open the throttle, I just walked away for the night.

    i never saw a fuel pressure issue. It had 54-58 psi at all times.

    I'll try it again in the morning with a cool engine. I'm more than disappointed that this is happening. My original PF 2 never had a problem....ever. I'm not sold on the "self learning" feature of these newer systems.
    Last edited by Heatsoaked; 07-30-2020, 08:04 PM.

  • #2
    The #1 problem with any self learning EFI system is: When there is a problem with a sensor, or fuel pressure. The system will now learn bad information, and store it into memory.


    Look for melted sensor wires first.
    Second. Try to start it normally. The cold motor settings should have never changed.
    Third. When the motor gets to 170F the "new learned settings" will kick in...Drive it right away to learn the old settings.

    You need to find out why this happened.
    1. Perhaps the fuel lines need some heat insulation?
    2. If using a fuel sump. The vent line might be plugged.
    3. If not using a fuel return line. One should be added.
    4. Perhaps the O2 sensor got too hot.
    At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy


    • #3
      Your inlet air temp is very high. It might start easier with a cold air induction system. Idle target seems a little low. Idle AFR seems a little lean. You can also slow down the self learning, or even shut it off for testing.


      • #4
        It fired right up this morning and ran great like usual. An inspection of the harness and sensors showed everything to be normal. Diagnostic screen showed all sensors green.

        I'm sure the heat was the issue. It's been in the 112-118 degree range here lately.

        Even though the fuel pressure showed good at 54psi, I'm wondering if the fuel isn't boiling. I'm using a remote sump behind the d/s headlight. There's really no direct airflow over the sump. It was hot enough I couldn't put my hand on it.

        This is an 85 K20 with 350 and headers.


        • #5
          I could bet the sump was boiling the fuel. In that heat you really need a return system and pump in the tank. 12.6 volts with engine on is low as well.


          • #6
            I really like rail mounted pumps over intank pumps. Once you have replaced a fuel pump with a full tank of gas. You will never go back to intank fuel pumps.....If I was into autocross racing, with a fuel cell, that would be a different story.
            At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy


            • #7
              The low voltage isn't actually the real voltage. It reads about 1.5 volts lower than what it really is. I have a thread on that on this forum elsewhere.

              The 165 air inlet temp is probably what the under hood temp is. Hmmmm.

              The PF2 I had for a decade came with a rail mounted pump. I liked it. Bite_Me makes a good point. I may go that direction. My dual tanks are going to make it twice as fun, and costly.


              • #8
                In tank pumps run cooler and and are quiet. In your area that is important. Not even counting there are less connections.