Yamaha 90 2 Stroke Water Pressure

Hey all. I have a 2001 Yami 90 2 stroke that has been an absolute beast. Love this motor!

I had my water pump done professionally a couple years back and, recently, the water pressure started to dwindle eventually making its way to sub 10 psi. So, I went ahead and bought a rebuild kit and just did it myself (that dad gom impeller key is impossible to get out, btw! ). I also tested the thermostat in some boiling water and it opened up just fine. Replaced the gasket and popped it back in.

Anyhow, I took the boat out last weekend and the water pressure still is around 10 psi. The overhead alarm isn't going off or anything, but I've had higher pressure before. Any thoughts?

 

The only hard component that was replace was the metal insert within the casing. I cleaned up all of the gasket mating surfaces and the base plate really well...so I don't think that's it. Where would this tee be that you speak of? That might be my next place to check. Also, where would I find the poppet valve? I could check that, too.

Good to hear from you again, Brett. It sure has been a while. I'm relapsing my fishing addiction...hopefully this time I never recover!

 

Hey there! The stream seems a little weaker than it should be. I mean...it still pees...but after I took it to Alafia Marine when I had it done professionally, it was like Mr. Ed.

Brett, I did look at that diagram after I read your initial response...love that site! Good prices on parts, too. Is there anything specific I should be looking for with that valve or the spring? I noticed it when I checked the thermostat and it wasn't stuck or anything. I cleaned out the hole and all of the areas with a dremel and very light wire brush.

Thanks for helping me with this guys...hopefully it's just something stupid that I can easily take care of without spending a bunch of money!

 

I love the CLR idea. Brilliant! I'll have to try that. Maybe even today! About what ratio to water did you mix the CLR in? Will this affect my seals or gaskets? And is the Salt Away completely necessary? If so, where can I find it?

I'm looking for a way to avoid tearing the motor apart...been there done that with my old Merc.

 

Okay so here's what I did...

My Yami has one of those silent flushing attachments that lets you flush it without the motor running. So, I poured some CLR in the faucet end of the hose, turned it on for a few seconds, and let it sit for a few minutes. Then I put some dish soap in the faucet end of the hose and followed the same procedure. I did this twice then did the silent flush with straight fresh water for about 20 minutes, then backflushed through the pee tube. I'll let you know if this has any effect tomorrow. If it doesn't do much, I'll give your method a shot.

As far as the pressure tube, it connects to the head. No tee joint or anything that I can see. Either way, the stream is what seems a bit weaker, not just the pressure read.

Brett, the PCV seemed fine when I checked the thermostat. It's definitely not worn or weak.

Gotta love this stuff!

 

#1 I ALWAYS run on the hose AND silent flush. If I only do one, I run on the hose to flush it.

I took the boat out Monday morning and the stream looks solid coming out of the pee hole. Now I'm starting to think it might just be the gauge...

I'm going to attempt the CLR in the bucket thing at some point over the next month or so and see what happens, too.

Keep the suggestions coming guys. You are a huge help, as always!

 

I'll have to price that out. Water pressure seems fine especially at higher RPMs. And alarm doesn't come on. If it does, it's usually because a bunch of grass kicked up on my LU and blocked the intake. Either way, I'd rather make sure it's tip top shape. May be something to use some Christmas money on. Until then, it's running, running great (for now), and gets me to my favorite spots. Hopefully no issues for a while! I'll keep you all posted. Keep your thoughts and experiences coming! Thanks guys!

 

So I went and got a price only to be told by one place that they had done similar jobs before and the labor costs would probably not be worth it. Another place (my main source for trusted motor work) priced me at about $350-$400. He said he is willing to take care of it but suggested I try something else first. The name of the product is Hammerhead Marine Descaler by Bright Bay Products. It's a biodegradable product that is safe for aluminum and attacks calcium and rust in outboard and inboard motors. Apparently it was originally developed for AC systems. They sell commercial systems to outboard repair shops and there are a couple in my area who were asking $250 for the service.

So, since I could get it manually cleaned out for $350 or so, I decided I would take matters into my own hands. I built my own little system with a submersible pump from harbor freight and the Descaler product is only $40. So for around $70 total, I figure I don't have a ton to lose. I'm waiting to receive the product in the mail and will keep you all posted with the progress. Hopefully this works and is a good option for some of you on this forum who may run into a similar problem or just want to prevent such a problem. I've seen a video of this stuff dissolving shells so I think it may at least help a bit. I've also heard some 3rd party testimonials that this stuff is legit and made a night and day difference.

 

Haha yes sir this is the first thing I checked, honestly. I disconnected it and ran some 80lb test through it to clear anything out that may be in there. I wanted to get rid of the simple solutions before moving forward with anything. Thanks for looking out, though