Apologies for the inexact wording I used Cap M. I should have said the full and proper phrase, "fuel flow transmitter" which is not far down the pipe from the fuel output of the HMU. It measures the flow rate coming out of the HMU on the way to the nozzles in the cans. It is an electromechanical device, converting fuel flow to an analogue signal.
The output of the transmitter goes to the EEC, located on the fan case, which communicates this flow rate via the ARINC-429 bus to the EICAS computers and fuel totalizer which sends this figure to the FMC for displaying and comparing CALCULATED to TOTALIZER fuel. For the classics, the fuel flow transmitter signal is monitored directly by the EFIS and totalizer units.