[Idu]

Originally Posted by Irace86.2.0

I just drained the fuel by running the car in accessories position with a fuel line attached to the feed. The pump ran, and the fuel eventually stopped after pulling 4.5 gallons out. I assumed the tank was empty, but it was not. I could only fill up 9-9.5 gallons of gas. There is probably 3-4 gallons left in the car. I am assuming the fuel is on the passenger side of the tank. My guess is the siphon didn't work to bring fuel over to the other side.

For disclosure: I have a K24 swap (shouldn't matter); I have eliminated the Fuel Pump ECU (shouldn't matter); I have eliminated one of the fuel lines (shouldn't matter); I shortened the purge line, which is now vented to atmosphere (shouldn't matter); the car was somewhere around half a tank; the car was sitting for 6 months.

You say the fuel pump will only run for a few seconds. I'm guessing this is because the Fuel Pump ECU determines the fuel pump only needs to run for a few seconds to build pressure because the car is not started. I believe the Fuel Pump ECU steps up voltage depending on the algorithm. In my case, the fuel pump just ran constantly up to the moment when fuel stopped flowing after ten minutes or so and 4-5 gallons later, and then I shut things down. When I filled up and put the accessories on, I heard the fuel pump kick on, and it was loud, and I heard fuel flowing, but then I assumed the pump continued to build pressure until the regulator told the fuel pump to stop flowing or to slow down to maintain pressure. I don't know.

The question is why didn't the fuel pump drain the tank entirely? Does the passenger side get pulled via the fuel pump, or does the right side fill the left side using some type of Venturi effect or something?

Can confirm that a car with the stock engine/fuel system does not keep the fuel pump running for more than a second or two on ignition power. Sounds like something you changed with your swap made what you did possible.