Ok, I have a new fuel filter, and I am ready to put it on, which is no problem. My problem is, where, or how do I depressurize the fuel lines? I have a 1991 F-150 5.0 4x4..... Please help.....

 

There is a schrader valve on the fuel line to the left of your distributer. I use it with my fuel pressure gage to depressurize the system.

 

The easiest and safest way... Pull the fuse (or relay) out of the Fuel Pump circuit and start the truck! It will run for a few seconds (until fuel pressure drops) and then quit. Try once again to start your truck to ensure that all pressure is gone... Then change your filter.
Also, You WILL get fuel on you when you disconnect the fuel lines... Wear eye protection! Have an extinguisher handy (it is GASOLINE) and wash the gas off as soon as possible. Gasoline is a Carcinogen and will be absorbed through your skin.

 

I'm not sure on a '91, but on my '93 there is a safety fuel shut off. I think it's called an inertia switch (shuts off fuel in a collision). Mine is behind the passenger side kick panel. You just push the switch and start the truck - let run out of gas and the lines are depressurized. Check your owners manual or shop manual if you have one. Hope this helps.

 

in my 1990 it is on the drivers side behind the brake off to theleft on the firewall...greay cylinder with a slot push down the button on top till you see red in the slot