How hard is it to change the sender in the gas tank?

If it is showing that it is empty, the float may have sank. However, the cause could be the gauge in the dash or the sender and the sender is in the tank. It is not easy to change because you have to drop the tank. It is cheaper to replace the sender than it is to change the dash because the dash guages are all on one unit. However there are tests that can be run to see what the issue is and the tests are done using meters and jumpers etc to see if the guage responds to those. Then they know whether it is the sender or the guage.

this problem sounds like the fuel level sender in the gas tank is not working and needs to be changed. not many problems are in the dash in these vehicles so I would definatley go to the gas tank sender first.

Perhaps you might consider the sending unit in the gas tank.

Sounds like you have a broken tank or tank connection. The sending unit ( hanger ) has the gas pump and the gauge sender in the one unit htatgoes into the top of thetank. the tank has to be lowered to see. theirs three lines connected with snap on fuel connecters that take a line toolto release them. some methinol fuels will eat the seals out of these and rot the float for the fuel sender. If the tank has been hit hard from the bottom theirs a baffle that can come adrift and run into the hanger breaking the lines as they go though the top of the tank making a leak course you coulda run over something that punctureed and bent the tank.

Either your gauge is bad or the fuel level sender is. Most likely it's the sender in the gas tank. To replace it you would have to drain the fuel tank and pull the fuel pump/sender assembly and replace. You cannot just replace the fuel level sender with this car, the entire assembly must be changed out.

There is a TSB for this issue ( TSB 08-2-9 ).

The problem is high sulfur content fuel will cause a problem with the fuel level sending unit, and cause it to read incorrectly.

The 2 times I had this happen, I was not at my normal brand fuel ( had it happen with Shell fuel both times ).

I fueled at 1/2 tank with my normal brand, and then after another 1/2 tank fueled again, and the problem went away.

If you want, the TSB lists new revision fuel level senders, that you can drop the fuel tank, and replace your exiting one with to cure the problem.

The correct P/N depends on your truck cab & bed config, and options

PART NUMBER PART NAME
8L3Z-9A213-E Kit - Fuel Sender 2006 starting 12/8/2005 through 2008 - FFV-26 Gal Tank - 126/132 WB
8L3Z-9A213-F Kit - Fuel Sender 2006 starting 12/8/2005 through 2008 - FFV-30 Gal Tank - 139 WB
8L3Z-9A213-G Kit - Fuel Sender 2006 starting 12/8/2005 through 2008 - FFV-27 Gal Tank - 145/151/163 WB
8L3Z-9A213-H Kit - Fuel Sender 2006 starting 12/8/2005 through 2008 - FFV-36 Gal Tank - 145/151/163 WB
8L3Z-9A213-A Kit - Fuel Sender 2004 through 2008 - Gas-26 Gal Tank - 126/132 WB
8L3Z-9A213-B Kit - Fuel Sender 2004 through 2008 - Gas-30 Gal Tank - 139 WB
8L3Z-9A213-C Kit - Fuel Sender 2004 through 2008 - Gas-27 Gal Tank - 145/151/163 WB
8L3Z-9A213-D Kit - Fuel Sender 2004 through 2008 - Gas-36 Gal Tank - 145/151/163WB

well either the fuel sender got caught on the tank baffle or your other sender was going bad

There is a TSB on high sulfur fuel usage, and how it impacts the fuel level resistance.
If you change fuel, it might start working again. The TSB is : ERRATIC FUEL GAUGE OPERATION TSB 08-2-9

Publication Date: January 22, 2008
FORD: 2004-2008 F-150
LINCOLN: 2006-2008 Mark LT


ISSUE:
Some 2004-2008 F-150 and 2006-2008 Mark LT vehicles, built before 12/3/2007, may exhibit erratic fuel gauge operation or illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0460 or P0463, and/or Instrument Cluster Module DTC B1201. This may be caused by sulfur contamination in the fuel causing an open or high resistance in the fuel level sender.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

Install a new fuel level sender following the service procedure instruction sheet provided in the fuel sender kit.

PART NUMBER PART NAME
8L3Z-9A213-E Kit - Fuel Sender (2006 starting 12/8/2005 through 2008 - FFV-26 Gal Tank - 126/132" WB )
8L3Z-9A213-F Kit - Fuel Sender (2006 starting 12/8/2005 through 2008 - FFV-30 Gal Tank - 139" WB)
8L3Z-9A213-G Kit - Fuel Sender (2006 starting 12/8/2005 through 2008 - FFV-27 Gal Tank - 145/151/163" WB
8L3Z-9A213-H Kit - Fuel Sender (2006 starting 12/8/2005 through 2008 - FFV-36 Gal Tank - 145/151/163" WB
8L3Z-9A213-A Kit - Fuel Sender (2004 through 2008 - Gas-26 Gal Tank - 126/132" WB
8L3Z-9A213-B Kit - Fuel Sender (2004 through 2008 - Gas-30 Gal Tank - 139" WB
8L3Z-9A213-C Kit - Fuel Sender (2004 through 2008 - Gas-27 Gal Tank - 145/151/163" WB
8L3Z-9A213-D Kit - Fuel Sender (2004 through 2008 - Gas-36 Gal Tank - 145/151/163"WB



WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage And Emissions Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME
080209A 2004-2008 F-150, 2006-2008 Mark LT: Install New Fuel Level Sender, Includes Time To Remove And Install Fuel Tank (Do Not Use With 9002A, 9002A4, 9002A6) 1.9 Hrs.

DEALER CODING
BASIC PART NO. CONDITION CODE
9A299 42

Bad ground from your fuel gauge sender. Find a good ground on your sender and I would bet it will work properly...

hello, it sounds like it has something to do with your fuel sending unit located inside your gas tank,on the sending unit it has a float arm that reads the fuel level, some times that float arm gets jammed and wont show your actual fuel level,to fix this with your gas tank at least half full use a rubber mallet or any other object that wont damage the tank and with your key in the start position with the car not running but reading your gages hit the gas tank not to hard but hard enough to lodge the float arm loose, if this is unsuccessful then it will probably be a bad fuel sender location sensor located on the actual fuel sender if that's the case you'll need a new fuel sender. good luck and please send me a update or any questions let me know.