mechanical- by actual fluid.
electrical- by sensor.


correct me if im wrong

 

just get the b&m one that goes ontop of the fuel filter, if you want it in the cabin get an electric one.

 

is the electric one just as accurate.?

 

I personally have no comparison for you, i have the mechanical gauge and it reads great. I dont have it in the cabin, but im tuned with a burnt chip and confident i dont have to worry about my fuel pressure. I assume the sender unit operates as a mechanical one would, only it converts the readings into a signal that sends back to the gauge.