seen a youtube video where you take the furl pump out on each side clean the contacts on the floats using a qtip and should work .. if not then need a new fuel pump assembly for each side i thing..

 

Easier way is to just measure resistance across pins 2 and 5 on the pump main harness and see if the resistance value is between 4-80ohms depending on fuel level, sub harness on the other side should be 3-43 ohms. If the resistance is wrong then the problem is the floats sending the wrong fuel level to the combination meter, if the resistance is correct then it's highly likely the combination meter is bad, very slight chance that the wiring between the two is damaged.

No tools needed except a digital multimeter, no tearing apart stuff needlessly and risk getting gasoline on interior components, rear seat removal takes all of about 10 full seconds start to finish.