my engine light has been on for a while,used a code reader and got a p1450.ive noticed my fuel mileage has been down a bit since the light has been on.anyone else experience this.also ive noticed when i put gas in my gauge doesnt move until the truck has been turned off a few times.

 

A quick Google search resulted in this:
HX18 DTC P0446 OR P1450: CHECK FOR VISUAL CAUSES OF EXCESSIVE FUEL TANK VACUUM

Continuous Memory Diagnostic Trouble Code (DTC) P0446 or P1450 indicates that Self-Test has detected the Evaporative Emission Control System has excessive fuel tank vacuum. Also, a DTC P0446 indicates a vent control malfunction.

Possible causes:

-- EVAP canister purge outlet tube (EVAP canister purge valve to EVAP canister) blockages or kinks.

-- EVAP canister tube (fuel tank to EVAP canister) blockages or kinks.

-- Fuel vapor elbow on EVAP canister contaminated.

-- Restricted EVAP canister.

-- Canister vent (CV) solenoid stuck closed (partially or fully).

-- Plugged or contaminated CV solenoid filter.

-- EVAP canister purge valve stuck open.

-- Fuel filler cap stuck closed (no vacuum relief).

-- VREF circuit open in fuel tank pressure (FTP) sensor.

-- Damaged FTP sensor.

 

so its been a while and just havent had the time or money to fix it.basically i replaced the evap canister and fuel seperator.there is nothing else running from the canister on my truck no hose or anything. iknow theres parts missing obviously.ijust dont know what i need to pick up.any help would be great thanks

 

You have parts missing?
How did that come to be?
The fuel system test the PCM does is very complex and takes some time to perform.
All the hardware must be in place and good before the test will complete.
There is a pressure sensor, vent solenoid, vacuum line etc. that are under control of the computer.
The fuel level signal is an analogue voltage signal to the dash according to the float arm resistance value.
In the dash it's converted to digital then back to analogue to move the indicator.
There usually is no delay after fueling but there is some time delay in updating the gauge after drive cycles take place and during driving.
I suspect the system is not reacting correctly to the cap being taken off for fueling. Otherwise the fuel level is not 'directly' tied to the tank diagnostics.
The pressure sensor likely is sending the wrong signal at refueling time and affects the update time interval..
Good luck.

 

after the evap canister and fuel seperator.there is nothing running back to the tank.i assume there should be something running back from it.not sure what happened.

 

after the evap canister and fuel seperator.there is nothing running back to the tank.i assume there should be something running back from it.not sure what happened.