This streak, when the fuel tank is difficult to fill, is because the valve in the tank is stuck. You cannot repair this. You need to install a new gas tank. There is a thread somewhere on this forum where a gas tank was pulled from a 3rd gen and taken apart to show the failed part. I had to replace the gas tank on my 2005 R a few years ago for this exact problem.
When you first turn the key on, the fuel pump must run for a few seconds to prime the fuel system. Then, after the vehicle is started, the fuel pump should run continuously. If you are losing fuel pressure after the fuel pump has been running for a few minutes with the engine and there is no leakage anywhere between the fuel pump assembly and the engine, then there is a possibility that the regulator in the fuel pump assembly is allowing fuel to flow back into the tank. Or somewhere else in the pump Fuel is being dumped back into the tank.
Another possibility is a bad fuel pressure regulator. Generally, when the fuel pressure regulator goes bad, it leaks and fuel is sucked into the vacuum hose and then into the intake manifold. Sometimes you will get an error code for too rich. Sometimes you won’t, and the fuel trim would be on the downside. You can check this by turning the key on and letting it fill and then pull the vacuum hose off the regulator and see if it is wet with gasoline. You can also check the operation of the fuel pressure regulator by starting the car and see if the fuel pressure increases by squeezing the vacuum hose. Without vacuum the pressure in the lines should increase and with empty vacuum the pressure should decrease.
Since you replaced the fuel pump unit, my question is where did you get the fuel pump that you installed? If it was a cheap pump assembly, it might be bad out of the box. There is a regulator in the fuel pump assembly to help increase the pressure in the pump to be able to push the fuel up to the engine. So the aftermarket pump may have a problem with the regulator in the assembly or with the actual fuel pump that came with the assembly.
Another possibility is that the fuel filter is not properly attached to the fuel pump assembly, which would allow fuel to be thrown back into the gas tank.
Then you have the electrical side. A poor ground, fuel pump relay, battery or alternator are all other possibilities.
