water pressure problems

[giddy_up]

On my 2000yr yam 200hp outboard.

I had an overheat alarm and noticed that my water pressure gauge was fluctuating between 1 and 12psi. This seemed to happened more at higher revs.

The higher the revs the less the pressure.

Itook the lower unit off cleaned out any bits of sand etc. REplaced the impeller and water pump housing.

WEnt for a sea trial and the pressure was fine until going above 3500 revs then it started to flucauate.

Do you have any ideas why it would be doing this.

thanks in advance

scott
:'(

 

[giddy_up]

Re: water pressure problems

meant to say fluctuate

 

[KCLOST]

Re: water pressure problems

Just a quick question, are you sure you don't have the motor mounted too high? Possibly drawing the intakes up above the surface of the water...

Is this a sudden occurance and has worked fine before with the current set-up...

The fluctuation could occur as a result of the motor being too high the pump going out, possible air pocket at the intakes (which is unlikely). Also there is a pressure relief valve that opens around that rpm level that will cause the pressure to drop, but it should gain again with increased rpm to WOT...

At what rpm level did the alarm go off?