Replaced Fuel pump and now can't pump gas into truck. What is wrong?

I have a 2008 Tahoe Ex-police truck. I had to recently replace the fuel pump on the truck. 142,000 miles on it. I had dropped the tank and had more then 1/2 a tank of gas in it. I was able to get a siphon hose done the fuel neck to get gas out so I could have a light tank to install back into the truck. After I did this I am now having a issue with pumping gas into the truck.

As the gas goes in it keep coming back up the neck and splashing back out. Almost like there is no vent line. Or something is clogged. I had ran the tank back to 1/4 tank and just dropped the tank again to check all hoses and wanted to check in the neck. There is a metal piece/part in the fuel neck that pushes up and down. I thought maybe I screwed this part up when I pulled the Siphon hose back out. But this metal piece/part moves freely and all lines are connected and nothing looks pinched. I even blew some air through it.


What could be the issue?

Thanks for any help Jason

Sounds like a issue with the filler neck.

Might be a ball valve in there or something could have been damaged when you siphoned with the tube.

Might do some reading on how the filler neck works or if the filler neck has any type of roll over safety valve.

Thanks for the reply. I pulled the tank back out again and found my issue. I rushed to get the tank back in so I could use the truck for work. Instead of taking the vent line and putting it over the cross member. I left it underneath and crushed it closed. I only figured this out after pulling the tank. I grabbed some channel locks and squeezed the tube back open and put it back over the crossmember and went to the gas station and gas goes in no problem.