2004 hpdi 225hp low water pressure

[mvanosdale]

What may be causing my boat the idle at 0 water pressure and only get up to maybe 10-12
psi while WOT. The motor had the #1 cylinder go down. It was rebuilt. Before this happened. Motor had 20-25 psi while running. I’ve had my mechanic replace the water impeller and still not change. What should I look at doing

[mrdeath]

My HPDI doesn't register anything at idle and never has. Prior to this year, it has always ran 20 plus at WOT. It's been a lot lower this year so I went to replace the impeller and it looked brand new. I had just had the prop shaft replaced so I assumed they put a new impeller in it. It's not overheating, not even close as I can see the digital temp on my graph. I've hooked the hose up to the flush port and let it run for a while to clear anything out that may be lodged inside and still no change. I'll probably go ahead and put the new impeller in this winter, but for now I'm just running it and keeping an eye on the temp. Oh, I also disconnected the hose from the pressure sensor and the gauge and blew compressed air though it to clean it out. No change after that.

[reelmin5]

poppit valve!

[captdwayne]

I have the same issue with my 3.3 HPDI. It'll run around 15 - 20 when cold and drops to12 WOT a few minutes later after getting warmed up good. I've changed the impeller, checked and cleaned the poppit, checked the water pressure line to gauge, and checked thermostats. Ordered new thermostats and going to install soon. The pressure will be lower with the hotter temperatures we are having.No over heating alarm.

[21XDC]

poppit valve!

Yes