Understanding the CAN bus system.

[moresparks]

Dumb question alert!!
I am trying to understand the CAN bus system on modern engines and specifically fuel data.
On modern MPI engines with data harness connected to the dashboard and gauges, how does the gauge read data? For instance on a tacho, there is a small LCD display that gives a host of engine warnings which includes fuel flow. Am I correct in assuming that fuel flow is via CAN+ and CAN-? Although on my data harness there are also connections for oil pressure, temperature, trim and tacho etc, but I cannot see fuel!!
Thank you.

 

[spannerman]

The ECU on the engine collects data from the sensors and sends it in data packages up to the instrument via the canbus, fuel data is extrapolated from rpm, injector on time and throttle postion, this will give gph or lph and if you have a speed input signal from a paddle wheel or gps it will give you mpg and range.