Water pressure issue/ 200 sho

[rockangler]

I recently purchased a 200 SHO. After about 9 hours of break in I started having water pressure issues. I was running around 5000 rpms and water pressure was right above 23 psi. Water pressure started dropping. it dropped to around 13 psi and then back to 23. It continued doing this all the way back to the ramp. I took it back to the dealer. They went through the lower unit, changed the impeller and some screens on the lower unit. Next time out it continued to fluctuate as before. I talked to the dealer again today and they said the Yamaha tech said that as long as it dosent drop below 11 PSI it would be ok. I have never seen a motor fluctuate like this in 25 years of running a bass boat. Any suggestions on what would cause this. PS: I pressurized the line from the motor to the gauge and pressure held so it is not a line leak or bad gauge. The dealer preformed the same test with the same results.

[champ223]

They run high volume low pressure on the sho. Can’t say I’ve ever seen mine go as high as your saying but it is routinely at 12-15 psi. I know you said the gauge is holding pressure but Any way you can change the gauge for another? It could still be a bad gauge

[Rich Z]

Its normal for water pressure to fluctuate. Have seen mine go up 10psi and than drop 10psi and that comes from t-stats opening and closing. Normaly it will sabilize on longer runs around 17psi at higher rpm.

[Triton19x2]

Its normal for water pressure to fluctuate. Have seen mine go up 10psi and than drop 10psi and that comes from t-stats opening and closing. Normaly it will sabilize on longer runs around 17psi at higher rpm.

Agree with Rich....usually the only time it does not fluctuate is at WOT...mine will stay at 20 @ WOT

[rockangler]

Its normal for water pressure to fluctuate. Have seen mine go up 10psi and than drop 10psi and that comes from t-stats opening and closing. Normaly it will sabilize on longer runs around 17psi at higher rpm.

So this
is normal for four strokes? This is my first four stroke. I never noticed this with my HPDI.

[Rich Z]

Normal when water is cold. You wont notice this in the summer. Unlike most two strokes the SHO doesn't have a pressure release valve so the pressure seems to be controlled by the t-stats.