I have a 2004, 150hp  XR6.  What range of water pressure should I expect from idle to WOT?  Currently, I'm getting around 5 at idle to around 15 at WOT.  These pressures seem to be really low to me, so I need some input from you pros.

I just checked the owner's manual for my 150.  It's a newer model, but the only thing it says about operating the engine is to check to make sure there is a steady stream of water from the water pump indicator hole, not a word about the pressure range.

The owners manual does say the water pump impeller and housing should be checked/replaced every hundred hours.

At idle, mine shows the needle just off the stop pin.  At wide open, it runs about 15 - 20 pounds. 

The tech told me that the main thing is to be sure there is a strong steady stream from the indicator hole.

He did recommend getting the pump checked at least once a year, more often if the boat is operated in water with sediment suspended in it.

Will have my water pump checked out.  At the very least, the impeller will be replaced.  If there is the slightest question about the housing, it will be replaced too.

If the water pressure for your engine has dropped, it would indicate wear on pump components.  Replacing the pump is cheap insurance.

Thanks for the input Tom.  I replaced the complete pump, t-stats and poppet valve about six months ago.  After the t-stats open I have a good water stream.  You are right about the Owner's Manual not giving any information about what water pressures are to be expected.  Neither does the Seloc Maintenance Manual.  For some reason I've got it in my head that the water pressure should be around 20psi at WOT, but I could be way off base here.

If the water pressure for your engine has dropped, it would indicate wear on pump components. Replacing the pump is cheap insurance.

Rhino is right. I have a Merc 250. The impeller was changed this past spring. At idle I get 5 psi. When running wide open I get 18-20 psi. I've always heard that when running wide open that you should never drop below 15 psi. Every outboard motor I've ever owned Johnson, Evinrude, Mercury, Yamaha have all got 5-8 on idle and 18+ WOT, providing my water pump components were in good shape.

Your water pressure line or gauge may have a leak as well. Thats a cheap fix too, just another piece of tubing. I'd check that first just to make sure.

My 1984 2.0L 150 Mercury runs 8 PSI at idle and 20-25 PSI at WOT with the motor level. Once I trim it out for top speed, I usually run 18-20 PSI.

If everything else checks out, there might be a problem with your water pressure gauge.

15psi is Fine a WFO I have no popit and no thermostats and have about 13psi At WFO remember guys our motor work more off of water volume then water pressure

15psi is Fine a WFO I have no popit and no thermostats and have about 13psi At WFO remember guys our motor work more off of water volume then water pressure

From what I have been told, it is not a good idea to run without poppets and thermostats. I am no outboard mechanic though. I would not run my motor that way.

15psi is Fine a WFO I have no popit and no thermostats and have about 13psi At WFO remember guys our motor work more off of water volume then water pressure

From what I have been told, it is not a good idea to run without poppets and thermostats. I am no outboard mechanic though. I would not run my motor that way.

X2, there is such a thing as cold sieze. It happens when you bust off from the ramp without a good warmup in the colder water.

I should have stated my motor is highly modified.But it is a steel bore. I run a 1 piece adapter plate and it is dry stacked. and I have no popit i only have a popit cover with a dump hose out the back of the motor. I dont have thermostats instead I have washers with with 1/16 holes in them and i have a hose from each head that dumps out the back and I have a hose that comes out of my 1pice plate so i have 4 pee hose coming out the back of my Alien cowl im just saying that i have all of these dumps out the back of my motor and it works fine with around 13psi and i know about the could seaz  I all ways let her warm up good before i hammer the MERC