I have a 2001 f150 7700 and when i plug it in to the computer it tells me that my fuel tank vac will not bleed up . How do you fix this ,

 

What is the actual DTC number ?

 

Fuel tank testing by the OBDII is quite complicated.
There are a number of codes to help define the problem.
What codes to you see?

 

the code is p1450

 

After doing some research and entering the part of the test routine that deals with this code; the following are possibilities.
A. Kinked or blocked line between the tank and Canister.
B. Fuel cap vacuum relief stuck closed.
C. Restricted Evap cansister.
D. CV solenoid stuck open.
E. FTP fuel tank pressure sensor fault and related wiring.

This is "part" of a test used to evaluate for a leak condition compared to a .040" calibration standard.

Look at the EVAP CAN assembly, the lines between and the tank sensor and the fuel cap for the fault.

 

thanks i will give that a try