I have a 2001 GMC Jimmy that all of sudden won't allow me fill gas with a gas pump, but I can pour the gas in with a gas can.

You really need a garage to diagnose why. You may have insufficient fuel pressure, or the injectors may be blocked if you have been running the tank low.

But first, check this fuse in the Engine Bay
ECM ICiN PCM/VCM Ignition, Injectors, Crank Sensor, Coil Driver Module

https://fuse-box.info/gmc/gmc-jimmy-1995-2001-fuses-and-relays

Low fuel pressure is mentioned here

https://www.google.com/search?q=96+gmc+jimmy+won%27t+start

Good luck with the move Tammy
..

you say it won`t start unless primed I take it you have to supply a fuel source. if so check fuel pressure as the pump maybe failing.

Those hoses are located in the same area as the tank filler. There is a set of hoses that go from the gas cap connection to the tank. You have to lower the tank.

check the fuel pressure reg. valve n see if it still holding pressure if not change valve

A malfunctioning antitheft system can turn off injectors causing just such a problem. Look for a light on the dash that says SECURITY or ANTITHEFT. If this light is present, go to this link for help.

http://vatspasslockpasskeysecurityhelp.yolasite.com/

add fuel to your gas tank.

if it has the vortech motor the gas pump most likely went bad.

I think they are the same on 1992-2001 On a 1993 the fuel pump in the gas tank. you will have to siphon gas out of the tank (as much as you can) before working on it. Disconnect the tank filling hose. Unbolt the tank, and drop that it down. There is a damper on the pump that may also be defective (dead) which would cause a hard start because of the lack of pressure in the line. Optional: Recommendation, as i have replaced many of these fuel pumps now. Cut a hole in the deck while the tank is out. This way, you can simply reach through the deck and pull it out of the tank if it happens again. Make sure You machine screw a sheet metal plate over the hole and replace the carpet.

Sounds like the gas tank vent is blocked, not allowing the air to escape as you fill. You should see two tubes going into the tank, one to fill, the other is the vent. Check it to make sure it's not blocked.

The only other thing, is if there is a mesh filter in the fill tube, and if it's blocked, it won't fill.

check the fuesable link!!