I have a problem. My husbands truck has dual tanks. The front tank does not work. Cuts off at about 1/4 full. So he never uses it. Well hes replaced the selector valve and fuel pump and as of today hes not getting any diesel fuel at all. He went to pump fuel the other day, knowing his tank was empty, and the pump kept shutting off not allowing him to put any fuel into the tank. What could be causing this? He's looking for help and advice so if anyone could please call him at 386-527-6952!! Thanks!!

 

I don't know if this is the problem, however it could be the bottom of the fuel sending unit has broken off. Let's say it broke off about three inches above the bottom of the tank which would cause it not to reach the lower 1/4 tank of fuel. This could be the issue and that's what it sounds like if it works properly until the tank gets to the to the same level each time.

 

Yep, the 1/4 tank out of fuel symptom shows that the cone of failure has failed:

Fuel Tank Sending Units

(Look towards the end of that thread)

And the not being able to fuel the tank probably means the vent tube in the filler popped loose: