I have a 2001 Mazda B4000 that i recently had to replace the gas tank and the spout that runs from the truck into the tank. I was having a problem pumping gas into the truck. I would start pumping gas and the pump would kick off. I took it to a local repair shop and found that the original spout was rusting and pieces of it had fell down into the gas tank. This tank has a wire screen near the top as a means of theft prevention so it was catching all the rusted pieces from the spout. Those pieces had clogged up the wire screen so bad it wasn’t letting gas flow through and making the gas pump kick off. I was told to replace the tank and the spout. The repair shop called and told me there is no aftermarket tank for my truck and a new tank from Ford would cost $1000. He was able to find a used tank for $400 so i got that and they installed and the replacement spout. The pump is no longer kicking off but the problem i have now is when i pump gas as fast as the pump will allow gas is dripping out where hose from the gas tank clamps on to the trucks spout. I have taken the truck back 3 times now because of this and they keep tightening the clamp that holds the hose to the spout. I pumped gas today and noticed it was dripping gas again. If i pump gas slowly i don’t see any issues.
If they keep tightening it and it’s not working, then I suspect the filler neck is out of round - Picture a dent in the side of a pipe. No matter how tight you wrap a string around it, there will be a gap where the dent is.