Normal 90 hp water pressure values

[mdeture]

I am getting my boat ready for some cruising, and wanted to know if anyone knew what the water pressure should be for a 2004 90hp 2 stroke mercury. I wanted to check, because I noticed I only get about 3 psi when running on the built in hose connection (telltale is fine). Also, I have not checked it yet in the water, but I would like to know what were normal values for the water pressure at idle and WOT. Thanks in advance.

 

[brent doherty]

Re: Normal 90 hp water pressure values

I am getting my boat ready for some cruising, and wanted to know if anyone knew what the water pressure should be for a 2004 90hp 2 stroke mercury. I wanted to check, because I noticed I only get about 3 psi when running on the built in hose connection (telltale is fine). Also, I have not checked it yet in the water, but I would like to know what were normal values for the water pressure at idle and WOT. Thanks in advance.

not sure about yours but i have a 2007 yamaha f150 and at idle it is just a few pounds on the gauge. at wot in the water it is around 18 - 20 psi. hope this helps?

 

[ricksrster]

Re: Normal 90 hp water pressure values

Your tell tale is fine then you should be OK. If your impeller is new make a note of your water pressure while cruising and at WOT. This varies a little from motor to motor. The reading will be your normal with a new impeller. As your impeller wears this number will drop indicating it is time to change the impeller.

 

[Silvertip]

Re: Normal 90 hp water pressure values

What built-in "hose connection" are you talking about? If you are talking about testing pressure at the telltale, it should be abour 5 - 7 PSI at idle and about 15 - 17 at wide open throttle. No two engines will run the same identical numbers so the best approach is to install a new impeller. Then note the idle and wide open throttle pressures. Any deviation down the road is an indication that the impeller is needing attention again.

 

[mdeture]

Re: Normal 90 hp water pressure values

It have been using the built in hose connection for flushing the engine after use and running it on the hose. Otherwise, I appreciate all the help. I am off to buy new flares now.

 

[Silvertip]

Re: Normal 90 hp water pressure values

If you are using the flushing port with the engine running on muffs you are not getting a valid reading since the garden hose is providing some of the pressure. That flush port is to simply flush the engine without running it. If you are running the engine without muffs, you have probably destroyed the impeller.

 

[mdeture]

Re: Normal 90 hp water pressure values

The manual said I could run the motor using the flushing port. I guess I will try it with the muffs tomorrow.

 

[Silvertip]

Re: Normal 90 hp water pressure values

So where and how are you taking pressure readings if you have a hose connected to the flushing port?

 

[mdeture]

Re: Normal 90 hp water pressure values

My boat came with a water pressure meter on the dash.

 

[Silvertip]

Re: Normal 90 hp water pressure values

OK on the pressure gauge. Pressure reading with a garden hose attached will not provide the most accurate reading since you are dealing with house water system pressure which might be masking low pressure from the water pump. The only real measure is to drop the boat in the water and run it. About 5 PSI at idle and 15 - 17 at WOT is normal although no two engines will read exactly the same.