i hooked my genysis scanner up and have these 2 codes FTP sensor high voltage, and my 02 blazer wont let me put gas in it, anyone else had this happen????

 

What excatly do you mean you cant put gas in it?

Have you looked into the DTC troubleshooting guide on this website?

 

i literally am unable to fill the tank, the pump shuts off, if i pump slow as possible it allows fuel in, other than that it spits it out, im sure its not venting. wondering if the canister vent solenoid is working.

 

Canister vent solenoid wont cause that issue. There is a rubber hose about 1 inch in diameter that runs along side the fuel filler. That is the vent that allows you to fill the tank. Crawl underneath and see if its damaged or plugged in some way.