Gas tank problem

Yober · Newbie Joined: Jan 07, 2005 Posts: 1

I have very strange situation with my fuel "sending unit" (fuel float assembly).
When the gas is totally finished the fuel gauge on the cluster does not advise me on it. The arrow stays on 1/4 of tank. I took apart the fuel filter and float assembly (which is accessible through the trunk) and played with the float in order to see if there is any problem with it. Surprisingly when the float is in the lowest position the gas gauge arrow on the cluster goes all the way down and the yellow light is lit, when the float is up the arrow goes up and shows full tank. I have looked into the tank in order to see if there is any problem with the inner tray (so called pacifier), it looked OK , there was no any contact between tray and the float. I have measured the depth of the tank and the length of the fuel filter and float assembly in order to see if the filter gets pushed by the bottom of the inner tray, the result was OK - i.e. the length of the fuel filter and float assembly is 9" and the depth of the tank is 9 1/4". So no conflict.
For incase I have lowered the bottom of the inner tray by banging a couple times with 2x4 and the heavy hammer, the depth now is 9 1/2". I have put back all the fuel filter and float assembly. Now the arrow on the cluster showed me an empty tank and the yellow light was also lit. I thought that's it, problem is solved. Not at all. When I filled up the tank with gas the arrow went up just 2-3 dials higher then Empty line. I took car for a ride on a bumpy road in order to shake the float. Nothing happened, arrow was still on the same position 2-3 dials higher then Empty line. I unbolted the fuel filter and float assembly and as soon as blots were loosen up the arrow on the cluster went up and showed me the full tank (as it was indeed full). I said that's it , problem gone. Not at all. When the gas actually finished completely the fuel gauge arrow staid on a bit lower then 1/4 full and did not advise me that tank is empty. I took the fuel filter and float assembly out of the tank and put in the second fuel filter and float assembly (which came from my second TL used as a part donor). Same things were happening with this device as well.
My brain goes nuts

Any ideas what else can be done?