I thought this may help someone in the future. We recently bought a 1997 Ford Expedition 4x4 recently and within a month the fuel pump went out. We'll, the truck had 212k miles on it and it was expected but within another month the new one went out as well with no warning.

At this point I new something else was causing the problem but had no idea what. Just out of luck one day while the truck was running I happened to be standing near the gas door and it sounded like the gas cap was farting, when I removed the cap it had a bad vacuum in the tank. The trucks idle changed and it just ran better.

So I immediately changed the gas cap and got to looking for a reason why the tank was only venting through the cap. After dropping the charcoal cannister I found my problem, the vent line was plugged with dirt! It is routed into the frame of our trucks but over time dust collects inside the tube. The vent tube also has a screen inside, so I just removed it all and reinstalled the cannister.

I would like to know how long someone has been chasing there tail with this problem! The original pump I removed was not a motorcoach, so it had at least failed once before. I don't know if this will help anyone but figured I would post it anyway.