Merc 60 4 stroke 4 cyl High Water Pressure

[Lowbrass000]

Looking for help.... While out fishing i noticed the tell tale stream was really strong at idle. Afrer giving it some gas the stream increased its distance up to 20 ft behind the boat. The water pressure gauge was pegged out at 3000 rpm. I have replaced the thermo and the impeller. Problem still exist with no load and the ear muffs on. Not sure what else could cause high pressure. The thermo is the aka poppet valve the my understanding
Can someone help clear this up......thanks?

[boats.net]

What is the serial number from your motor? Is this a new problem, or since you purchased new.

[Lowbrass000]

Definitely new problem. I remember when startup water pressure was around 0-10 psi. Ill have the serial number for you shortly.

[Lowbrass000]

Here is all of the info on the motor:

60 ELPT EFI
Serial # 0T990385
W700IRZ1
PN 891952
ECM # 0401 3/21/04
FAMILY # 5M9XM- 9952GE

If someone could also help me find a schmatic of the water flow system that would be a big help!!
The owners manual nor the mercury sservice manual has a diagram of this.

[boats.net]

Mercury water flow

You must have a blockage after the indicator and your water pressure guage fitting. I have attached a water flow schematic.


MERCURY 4STK WATER FLOW.pdf

[Lowbrass000]

Thank You... Ill take it apart and post my findings.

[Lowbrass000]

Still high pressure, the only way I can get the pressure to change is to remove the thermostat. I have cleaned all passages so there is no blockage. Could I have an exhaust gas problem? If so how do I check that?

[JUST-IN-TIME]

poppet valve and new thermostat

[Lowbrass000]

Already replaced