2004 330ci E46 Gas Tank Stops Filling at 1/2 Tank

[Masungit1]

The fuel pump on my 2004 330ci convertible stopped pumping gas to the engine/fuel rail; so, I replaced the fuel relay as well as the fuel pump itself (just to cover all bases). The car now runs great; however, after replacing the (right side) fuel pump, my gas tank now stops filling up at 1/2 tank. This problem didn't begin until I replaced the (right side) fuel pump. I've driven the car in this condition for 4-6 weeks and keep filling up the tank every few days, which is mildly annoying. I ran the car out of gas to test the dashboard warning light, emergency distance available, and physical tank levels; so, I know the tank is only filling up 1/2 way and matches the dashboard indicator. The right half of the tank seems to be filling up 100%, but then not spilling-over to fill the left side. I'm not sure of the fuel-balancing mechanics, but it appears the left-side fuel pump "jet" is triggered to keep the majority of the fuel in the right-side fuel tank, since that's where the fuel is supplied to the engine. After removing the right-side fuel pump (for the 3rd time) to inspect levels or blockage/pinched hoses, etc., I noticed excessive pressure in the rubber tube that connects to the top part of the right-side fuel pump with the left-side fuel pump "jet"; so, I replaced the left-side fuel "jet" pump as well (to no avail). The problem still persists and I am unable to fill-up my tank beyond 1/2 tank. The computer is not throwing any EVAP codes, but every gas station I've used throughout the last 4-6 weeks stops at 1/2 tank. I'm looking into a fuel vent valve under the hood and possibly charcoal canister, but will need a little help testing these components. Thank you in advance.

[Mless5]

I would think that if you replaced the right pump and the issue started to happen right after, I would be re-visiting that area. I had a similar issue on my friends e92 after replacing his main pump (pass side), but it turned out that one of the vent hoses wasn't seated all the way. I'd say make sure everything is seated correctly and is nice and tight. I also recall that you need to seat the large sealing ring on the tank first and than install the pump vs installing the ring on the pump and trying to install the assembly.

Good luck.