These valves are usually both connected to the output of the tachometric relay or oil pressure switch.

On bi-fuel, the switch used to change between fuels is used to turn off the tachometric relay.

In virtually all systems, the injection control system integrates the tachometric relay and closed loop feedback functions.

Where solenoids are fitted to the outputs of fuel tanks, these are also connected to the output of the tachometric relay or oil pressure switch.

In most modern installations, an electronic device called a tachometric relay or safety switch is used to operate electrical shut-off solenoids.

In most modern installations, an electronic device called a tachometric relay or safety switch is used to operate electrical shutoff solenoids.