I installed my FASS 150HD in July 2010. Ever since about October 2010 my fuel gauge hasn't been working like it used to. Once i get to about 150 miles on a tank, the needle just kind of sticks around 3/4 of a tank until i get to about 400 miles and then fill up again. Sometimes it will go as far as 1/2 a tank but then it stays and it still isn't right. I've been watching the trip ever since I first got my truck, and usually 300 miles is right at half a tank. For the past month the needle on the fuel gauge only goes down to about 3/4 of a tank until i fill it up.

 

Did you get the fuel basket back in the tank in the same orientation that it came out? Could be hitting the side of the tank or the float could have got bent? But either way to see what's goin on or to fix it the tanks coming back out.

 

I didn't put a draw straw in when i hooked up my Fass so I have never had the basket out. I wish I would've. and the return is running into the filler neck

 

I have the same problem with my fuel gauge but thats really a Dodge problem, every Ram ive owned has a fuel sending unit problem. Instead of doing a draw straw, im dropping the tank and installing a sump on the bottom of the tank, and adding a sending unit from Auto Meter to really know what kinda fuel i have

 

My buddy had a similar issue, his kept getting worse and worse. At first 1/4 was empty, then 1/2, and fianlly 3/4. It ended up being the fuel sender, of course. If I were to need a new sending unit I would get one of these:
Modified liberty fuel module

It already has the high flow draw straw installed, and won't give you any 1/4 tank issues. Return fuel from your engine, and fuel pump are returned to the fuel basket, keeping it as full as possible.

 

I am having the same issue. I replaced my flsu and while my bed was off I sumped it and installed an air dog 150 worked for a good 3 months then stopped working again...

 

I have the same issue with my truck and what happing is event worse .. I was filling a full tank and driving it to the 1/4 so i can calculate how is the truck use on fuel . Then i ended up runing out of fuel on a day after work but the gauge is not event go below 1/4 yet ... I call for help and got some diesel fill in but the truck is not start ...then after too many atemp i blew the starter feu ... So i have to call a tow truck to tow mine back to the shop ( my work place ) and tow truck is takes forever ... The time when my truck is broke down is 6 pm and i got home is 12 am . But not done yet : next morning i fill the truck with haft tank of fuel , check on starter , fuses .. Etc but the truck still wont start , it really a nightmare to me to find out what is wrong with it ... Then finally it start after i bleed the fuel lines ... So this is one bad exp i hade with the fuel gauge