fuel question...maybe odd, maybe not

[heff]

i know the fuel pick-up umbrellas are shot on my truck. Or i think they are. say my front tank is at 1/4 full, truck won't start, symptoms indicative of air intrusion. now if i switch to my full tank, truck fires and runs good. i can switch to the 1/4 full tank and truck runs just fine there too. also on the 1/4 full tank the truck idles really rough, and if it picks up fuel, truck really wakes up and feels stronger than it normally does.
is this a lift pump problem or something else?
replaced return line kit.
filter is full after sitting over night.
replaced filter with a filter without the goofy sediment bowl.
new italian made bb injectors.
timing is 8.5.
beru glow plugs. gp system is working like it should
no fuel leaking under truck or around tanks.
i'm not sure what could be causing this. sometimes it's a little harder to start when it's cold if the tank is nearing the 1/4 mark. *
first time i start the truck on a cold morning, it *might* be a little stubborn to start, kinda hit right off and idle rough until i kick on the cold idle.
immediately shut it down, gp cycle, truck starts right up.
ideas?
thanks in advance

 

[John Deere]

Sounds to me like you've got the right diagnosis. Shower heads are bad.

 

[Dieselcrawler]

Agreed

 

[icanfixall]

What you posted tells me you are correct about the pickups being broken off in the tanks. You can reach the front tank sender and remove it without droping the tank. Its easy. Just a punch or screwdriver and hammer to knock loose the retainer ring to the sender. Remove the fuel lines and one electrical plug. then lift out. Add 3 inches of rubber hose and one hose clamp.... Being careful to find that sender has a locating pin design in it and find the pin in the tank. Install the sender. connect the lines.. Your done.