2001 Suburban - Lost Fuel Tank Capacity

[lookinup]

Just replaced the fuel pump on my 2001 Suburban. After replacement, the fuel tank will not fill up more than about 1/2 way. Fuel gage works 'right'. When the tank will no longer take fuel, the fuel gage shows FULL but the most fuel put in since it was drained (to replace the pump) is 17 gal. When driving the gage goes down twice as fast as normal. Mileage hasn't changed noticeably. It just acts like the tank was cut in half.

 

Is there some type of evaporation or breather line that is messed up? I'm thinking a physical/mechanical problem, and chance this is electrical?

 

When the fuel pump went bad the Service Eng light came on. When I reset this there was P0446 code. I assumed this was a side effect of the pump being bad. [i guess I am still making the assumption that the pump was bad. Burb quit while driving ~60 mph. Would re-start and run for 1-2 seconds real rough and then die. Replacing the pump allows the engine to run normal.]

 

Any thoughts would be appreciated. Not the end of the world, but don't like hitting the gas station so often.