This 1999 Ford F150 came in with the SES light on and a code P0455 stored for a gross evap leak. I checked the obvious things like a loose or missing gas cap, okay. I also inspected the evap hoses and found no problems. I did a little bit of reading and found that I needed to check the vacuum source for the Evap Canister Purge Solenoid located at the left rear of the engine compartment and the pressure sensor at the rear of the tank. As luck would have it I found the problem at the vacuum line for the solenoid. It was stuck to the lower side of the EGR valve.
I pulled the vacuum line off of where it had melted to the EGR valve.
Cut out the damaged section and installed some thick walled 7/64″ rubber vacuum hose over the two cut ends.
The white piece in the picture below is the original vacuum line and the black hose to the left is part of the new rubber hose.
I talked with the customer about the repair and we concluded that he had probably moved the hose when he did a “tune up” and just did not notice it. These things happen.