Fuel Sending Unit
 

I have a 2004 RX8 and I've been having issues with the fuel guage. It seems to work fine up to the halfway mark and after that it stops working. I ran over something on that road that hit the fuel tank and damaged the fuel pump on the driver side which I replaced and I thought the fuel sending unit was part of the fuel pump so I thought the gauge would be fixed once I replace the fuel pump but the problem is still there. Any ideas? From what I understand the car has two sending units and one of seems to be working fine because it works ok up to halfway point. It has to be the one on the driver side. Does anyone have pictures of the sending unit or the location of it so I could get an idea of what to look for?

dude the wire that crosses over to the other side of the tank is supposed to fit into a little slot. its easy to dislodge it and if you do, it can get tangled on the fuel sensor (the floating one)set up. It may not let the float go to the top and in some cases it may not let the float go all the way to the bottom.
Remove the pump and look at the wire.
OD

There are 2 sending units..one in each side...they both mount on to a bayonet type mount. There are 2 wires that go from the drivers side one and attach to the fuel pump assembly...and through that to the plug. The passenger side one attaches to the port lid/, and through that to the plug and wiring harness

It is possible that one side wires are not hooked up properly..or the siphon tube is interfering with the movement of the floats

The wires are very small, and easily broken if they are stressed when removing the pump, or from any damage

hey ive been getting the EXACT same problem. is there any updates to this issue. I'm from Australia and I don't really want to take it to the Mazda Stealership.

need fix please :)

What happened to yours? It would be unlikely to be a problem unless someone had the fuel tank open

Either that or one of the 2 sensors has failed......

Well mine progressively failed to work...

it started by running out of gas at 1/8th (middle of last quarter) of a full tank.
then it started to run out at 3/8th (middle of second last quarter) of a full tank.

When I fill the tank up it works all the way up to the full line.

That's what happened to mine.

I also tried opening the tank where the fuel pump and sending unit would be, BUT i couldnt get the big screw lid off.

Any ideas?

IF you were to damage one of those wires how would one go about replacing them?

You could repair it with a crimp and some heat shrink...gas is relatively non-conductive..so that isn't a worry

The sensor is removable....think they want a fortune to buy new ones though...ask around..there are a lot of wrecked cars...and I doubt the fuel tank is a hot commodity

true they sell cheap ( partsgroup.com )

Had to wake this Topic up hopefully somebody answers, There are 2 plastic pig tails that hook onto the tank, one has 2 wires and the other has 4 wires. WHICH one plugs into the Fuel Pump Assembly, NOT the Sending unit assembly?

any success with this? i believe im having the same issue.