coltool
New Member
I have the 5.0 MPI engine that will run all day under 4000 RPM but the water pressure is showing only about 6.5 PSI. Above 4000 RPM I get a guardian warning which I believe is due to low water pressure. The engine only has 124 hours and the impeller on the pump was recently replaced, Engine temperature is showing 161 degrees. So either I have a pump issue or it is the pressure sensor. I read that I can possibly use the AC Delco pressure sensor but not certain. As folks have noted the Mercruiser part is significantly more expensive. I also see I may be able to install a "T" and gauge at the sensor location to compare what it is reporting to actual. That seems like an easy test as the sensor is readily accessible-not so much the water pump.