Fuel sender diagnostics

[irondoc]

Hi guys, one or both of my fuel senders is definitely faulty and I'm getting irregullar tank readings.

I've put my iidtool on, but can't work out which sender is faulty - does anyone know how this is achieved?

I have found 3 values - sender A and B voltage and "fuel mass". Sender A and B are reading slightly different voltages.....

Any help would be much appreciated

Cheers
Lucas