Please help - 0 psi block pressure

[Gcarroll18]

I have a 2002 mercruiser 5.0 mpi and battling 0psi block pressure. I have installed a manual gauge where pressure sensor goes to verify. Boat doesn’t overheat runs about 160 have replaced impeller and have backflushed system. Risers and engine all cool when running. I believe the water is just moving through so has no pressure. What creates pressure so I can keep it from going in guardian mode.

 

[GA_Boater]

Changed the thread title cuz "Please help" doesn't pique curiosity.

Are you getting any codes that lead you to what I assume is a water pressure fault causing Guardian Mode?

 

[Gcarroll18]

I can’t recall the # of code I have the two horn beeps and on computer it reads 0 psi at all rpms and says block pressure psi low guardian mode 5

 

[achris]

You have a thermostat in the housing? Without a thermostat, you'll fail to build pressure.

Chris.....

 

[Gcarroll18]

Yes I have a thermostat in. Water definitely flowing but no pressure

 

[GA_Boater]

Is the thermostat working?

 

[Gcarroll18]

Yes I’ve used two different ones to test. Has me kinda baffled because of course the computer needs to see pressure or runs crappy

 

[achris]

Quick test. While the engine is running, for a short time (up to 10 seconds is ok) pinch off the water hose between the power steering pump oil cooler and the thermostat housing. See if the water pressure comes up...

Chris.......

 

[Bt Doctur]

install a resistor to fake the computer