Thanks for the reply. I have made a mistake in the description of the fuel lines in as much as the facet is connected to the tank with dash 8 line and the line from the swirl pot to the 044 is also dash 8.katana wrote: ↑Sun Jun 05, 2022 6:47 am Some thoughts - feeding a 044 via a -6 supply is not advised as its much to small. Correct size is 12mm ID for decent gravity feed - too small, and pump will cavitate giving erratic fuel pressures. A 044 flows a LOT of fuel and if the majority of it is being returned to the swirl pot with a Facet trying to add to it, maybe the dash 4 vent is proving to be the restriction, so the whole system is becoming pressurised not just the pump to rail line?
All other pressure and return lines are dash 6 with the vent from the swirl to tank being dash 4.
With the filler cap removed from the tank, fuel can be seen flowing back into the tank from the swirl pot at all times
The system has always run perfectly well set up like this and the fittings on the swirl pot and pumps dictated to a certain extent the size of hose used