Just recently I keep hearing what sounds like a pump running in the egine compartment . . . I hear it when the truck is running and I am sitting in the cab . The dealership did the in tank replacement 2 years ago when my lift pump died . I have no clue what I will be checking for so any advice is appreciated .
Thoughts ?

 

They did remove the old filter mounted LP, didn't they?

 

Does your Cruise Control work??

 

I had a leak in the vacuum hose under the hose on the firewall. It would hum/buzz. It would buzz for 9 seconds, then quiet for 5, then repeat. Check that out.

 

Yup. There is a vacuum pump behind the passenger side battery. It runs your cruise control and the lines are brittle and break easily. I was brushing my engine off one day and bumped into the "T" where it goes under the cowl and mine broke. I got some rubber vacuum hose and fixed it. I still hear the pump on occasion but nothing like when the line had initially broke...

 

Sure sounds like your vacuum pump. Best to find and fix the leak as soon as possible, before your pump burns up from running all the time.

 

Thanks for the suggestions . . . I will look tomorrow and see . had dental surgery Friday that has kept me inside all weekend .