i know i know it's to new for this lol

ok so it's been awhile lol i got this po code problem with the 98 chevy po 452 low input it says 4.3 v6 vortec just replaced fuel pump on tuesday and the idiot light came on today after i put a 20 spot in the metal gut and 3 hrs later light comes on and i plug fancy little said code reader in and just clear the codes but it said evap sensor low input, and of coarse this genius cant find the manual for the sensor location can anyone refresh me some checked the gas cap twice thinkin it was loose to tight as can be no cracks

PO452 =Fuel tank pressure sensor circuit.
Sensor is on top of fuel tank.