Safety Flight,
"There are no caution for us pumps. Only when swithced off".
That is incorrect. There are cautions and they are driven by an "Amps monitor".
Essentially, if the pump is functioning normally then it should be drawing 1.5 to 6 Amps of current. If it pulling less than 1.5 amps then it has no fuel to pump and the caption will appear after 2 mins - the delay is to stop it cycling. If it is drawing no amps, it has failed or has been switched off - caption appears. If it is drawing more than 6 Amps then the fuel line is blocked, the caption appears.