90 hp Yamaha water pressure

I recently installed a working water pressure gage to this engine. The water pressure reads about five psi and will get up to about 11 psi if I revved the engine in neutral to fast idle . The stream coming out of the back of the engine, what I call the P whole is shooting a strong stream of water down into the lake that goes about 2 to 3 inches deep into the water. The impeller is probably six years old , And I am going to replace the impeller, but I'm curious what other gauge pressure's for a 90 Yamaha should be. Most of the stuff I have read says that most water pressure should be around 15 what are your all's thoughts

I'm not a mechanic by any means. I'd assume water pump is next after the impeller. My mechanic that works on my engine says that it is a good idea to replace the impeller every 5 years. Perhaps the pressure will go up after you replace the impeller. Lots of luck with it.

[QUOTE=CaptObvious;561965] I'd assume water pump is next after the impeller.[/QUOTE]

????
The impeller is the water pump.

I've owned 4 boats in my life, one with a 150 hp motor, one with a 115, one was a 60 hp and the one I have now has a 2006 90 hp mercury, it the same engine as the 90 yamaha just has a different name logo on it. and never had one with a water pressure gauge, I've replaced the water pump [ impeller ] on mine twice, I watch for the little pee stream when I start it and a good strong pee stream shows the water pump is working good.

ps, I made a video of replacing mine on a 90 hp Mercury and put it on youtube, it isn't a hard thing to do, watch the video and do it your self and save a buck or two.

" how to replace water pump 90 hp Mercury outboard "

Thanks guys. I'm on it!

Told you I wasn't a mechanic