It will eventually lose pressure, don't know what year your truck is but i'm guessing you may have pulled the 3rd pump fuse (only if 87-?) and the ones in the tank were still keeping the pressure up. Either way it will eventually stop and you can change the filter.

 

Never change a gas filter in a garage/enclosed place
I will only do mine outside

 

I think it is called the Shrader Valve.

 

thanks guys- its a 92 f150 4x4 5.0 w 115k. i was in the garage bc its 20* outside... but this job sounds like a summer job that i just dont have time for. so i'm sitting in monro muffler right now watching them handle the job. any other issues that might contribute to hardly any power in 1st gear under load? i've got no takeoff speed. thanks-

 

Pumps, plugs, wires, dist, cap, etc.. Basically anything spark or fuel related can have an effect on power. Also if the cylinders are gummed up or worn out you will loose major power.

 

If you don't mind, how much did Monro charge to service your fuel filter?

 

for the record: 38 bucks for service and 4 bucks for a "shop miscellaneous" fee. 41 total. needed done but didnt fix my power issue. onto cleaning up vacuum lines.

 

Sometimes it is worth paying to have work done, especially if it's cold outside. Good luck on finding your low power issue.