Fuel hand not working right .replace fuel sending unit,and spark plugs an wire,fuel filter the fuel hand read full but mileage say 150 miles to empty

The sending unit on the fuel pump is bad. It sends a signal to the gage to tell the fuel level. The reason the mileage is moving is because the sending unit is miss reading the fuel level. The sending unit for the fuel level is in the fuel tank.

Your fuel sending unit in tank is bad,may be incorparated with fuel pump or by itself.Car isn't going to drink gas that fast unless leaking.If tank reads a half,fill up to see if it's really half empty,and if it is half full,then your driving a gas hog.

I would bet the sending unit is bad but lets check it, a good test i use is that i have a used sending unit i connect to wiring to test the gauge and wiring, if the gauge moves when i move the testing unit then i know the gauge is good and the wiring to, locte the connector at fuel tank, and unplug it, this will be the one the leads to top of the tank and the connector will be on the side be the frame on drivers side, the way you know you have the right connector will be the truck will not run as this connector has the sending unit and pump wires in it, if the gauge goes to full then you know the wiring is good and the gauge is good, you can jump the two wires and gauge should go to full also. the problem is you must get the right wires for sending unit or you may pop fuse, let me see if i can get you a wiring diagram or just do the full test by unplugging connector.

Okay, your sending unit has a yellow and white wire, thats the sending unit wire, the other is a ground and we wont worry about that. so if you want to see if gauge will go to empty or full just unplug connector and gauge will move to full then if you take a wire and jump the yellow wire with white stripe to a good ground the gauge will go to empty, the thing is your gauge is on empty so sending unit may be grounded out, good day

A 100,000 mile tune up should include spark plugs, spark plug wires, fuel filter, if it has one under the frame(some newer cars have an in the tank fuel filter that is usually only changed when the fuel pump dies. Also replace the air filter if it is dirty and has been there over 20,000 miles. Some of the later models have coil on plug design and then there is no wires to replace. check tire pressure and the spare this also improves gas mileage.

Bad sending unit attached to fuelpump or most likely a crimped or chaffed wire to it, either inside the tank or outside.

check you mileage if the car has over 100,000 miles and you have not had a tune up it maybe time for spark plugs, air filter,fuel filter and spark plug wires if needed

You need spark plugs,and wires(or boots) and fuel filter,and air filter,and a pcv valve wouldn`t hurt either.

maybe the plug wires...did you mess with the timing?  Is the ox sensor wires connected?  Is a check engine light on?  Are you now running the a/c? 

you have two different problems. first your gauge may have a bad ground or bad sending unit . try fuel injector cleaner as they may be gloged for hesitation .

If you remove the sending unit in the gas tank, move it manually by hand as u saw done earlier, the gauge on the dash should also move. As long as the sending unit in the tank isn't 'stuck' at the half full level, the gauge should register empty to full as it moves. To be honest, I'm not sure if I would bother taking the sending unit out. 1st, u must be very careful not to blow yourself up when working on the gas tank (no sparks, etc), all u really need to do is fill up your car, see how many miles a tank of gas will go (carry a can of gas with u to see how many miles before u run out). If it's 350 miles, just set the trip gauge to zero every time u fill up, and get gas every 300 miles so u don't run out. If the sending unit moves freely, everything (wiring ) is connected properly, then it probably is the fuel gauge. good luck!