I have an 06 150 hp optimax (I bought the boat/motor new) It`s been serviced regularly, new impeller every 2 yrs. The water pressure gauge always showed around 0 at idle 5 when running. I know these gauges are not super-accurate and will fluctuate as the impeller wears, whats strange it the tech at the dealership found what looked like JB weld or Bondo covering the top two water intake ports on the lower unit housing it was painted black same as the motor. It looks like it was done at the factory? If anybody knows anyhing about this please let me know. Thanks

Blocking off top two intakes is pretty standard stuff, and should not affect water pressure.

I like 15, some can live with 12 at WFO, check the pressure tube from the motor fitting to the gauge to see if you have any restrictions, chances are you'll find a too tight tie wrap or kink.

Manual says 12 psi @ 5500 rpm

Idle 1.0 � 3.0 PSI
Poppet Valve Opening 4 � 9 PSI
W.O.T. 12.0 PSI Minimum

Too low at idle? -
�Poppet valve spring defective
(weak, broken, missing)
�Defective poppet valve seal
�Thermostat stuck open
�Severe internal leak
�Low output water pump
�Inlet restriction
�Strainer screen for air compressor
water supply is restricted

You can also attach another water pressure gauge to the "T" fitting on engine hose that runs to the boats water guage to check your gauge.

I've got a '05 150 optimax. I'm getting about 3 psi at idle and about 15 psi at WOT

My 05 150 Opti is running less than 1 pound at idle and 17 at full throttle through a three hole CLE lower unit. I added the third water intake due to low water pressure.