Hey All,

Looking for the water psi. I should be seeing on my 2018 Mercury 250 Pro XS 4-stroke at WOT? Getting conflicting information. Sounds like impeller replacement is a once a year deal on this engine.

Should be in the specifications section of your owners/operator manual.

Have you cleaned the strainers ?

Have Not. Just ran this new setup for the first time this weekend.

I replace impellers on mine every 2 years regardless of use. My 225 Opti runs around 15 psi WOT. My old Black Max 150 runs about 10 psi WOT. Both are 2-stroke though....

The original Owner has installed a new impeller each of the past 2 years but stated it never showed a high PSI at WOT. The Ranger dealer told him there was no problem just watch the temp. I have a good stream of water from the Pee hole and with a slight increase while giving more throttle but PSI only ranges from 1.0-1.9. This is on the analog gauge and also the Mercury smart gauge. Engine Temp runs around 130-140 degrees. My thoughts are it should show more pressure from the stream coming out.

if it was just the analog gauge with this reading I would say bad gauge or plugged/crimped hose. But the SC gauge is digital and I'm not sure where it gets its data from, maybe a sensor near the water pressure tube where both could be clogged but lets water flow thru the engine ok?

The Mercury Verado / 4 stroke forum on BBC would be the place to ask....

Have it on that forum also. No response yet

If you were only getting 1-2 psi there is no way your motor would be in the 130-140 degree faraihneght range

I am pretty familiar with these already having a 4.6 apart , send me a pm with a number.

I'm with you.. Thermostat Should open at 136... Not knowing which lower unit you have I figure you should have at least 15 Psi at wot. I've seen over 30 on my 2018 V-8..with sportsmaster
I wonder if the previous owner was one who started the engine while out of water ??
If it was mine I'd check the strainers first. If there clear I'd change impeller and go from there.

UPDATE: Shop found incorrect water pressure sensor installed on motor which appeared to be how it was done new. Also found a hose on the sensor that went nowhere. Installed the correct sensor and attached the hose. All pressures were now to Mercury specs. BIG SHOUT OUT and Thanks to Rockwall Marine. Something the first shop should have diagnosed from new.