We used to have a water pressure gauge on the pressure side of the water pump. (App. 35yrs ago) The one we used had a triggered switch when the water pressure dropped light and horn came on (most of the time this happened with crap blocking the RAW water intake/strain.
One time we had multiple problems on the same day caused by the low-pressure line collapsing and restricting the flow during high RPM’s on the motor. The shop sad this was caused from intake screen to small for the diameter hose and the new water pump to strong (Water pump was mechanical run of the fly-wheel)
I agree with fishaholic18, rig up another gauge and or add water pressure gauge. With a water pressure gauge you can see the drop in pressure as the impellers are worn.
Nils
