Not the water pump

I just bought a small rig with a 9.9 4stroke Yamaha outboard. It was not peeing water through the tell tale when I put it in the lake. Worked fine on garden hose but they can fool you sometimes.
Anyway, I pulled the foot off and the pump is perfect. Matter of fact it came apart so easily I suspect someone had recently installed a new pump. Now I'm wondering if the did not get the pick up tube connected when they reassembled it. The vanes in the pump were oriented correctly so that wasn't the problem. Any other suggestions?

mud dauber nest or cracked hose??

That would be my first thing to check. Making the assumption that on muffs water came out pee hole.

If it pees on the muffs, that tells me that the pickup tube was connected. My only suggestion would be to inspect the impeller to see if it has spun on the hub. I assume the key was in place when you inspected it. Are the rest of the pump parts in good condition? Housing, bottom plate, o-ring?

Ahh the key

Thinking about it last night I also wondered if the key wasn't installed. Soon as this weather calms down I'm gonna check. Thanks guys.

Well, that would have been too simple. The key is in place and it is obvious the water pump has just been replaced so aside from the pick up tube not being aligned I'm at a loss. Under pressure from the water hose hook up the tell tale hole sprays out a good stream, which makes me think the pickup tube had to be connected or water wouldn't have made it up to the tell tale.
I'll put the foot back on and see what happens.

With the water hose pushing out a good stream, seems to me the impeller isn't picking up a suction for some reason.

Possibly they didn't orient the vanes correctly to match the rotation of the drive shaft. However, years ago I took a course on small outboard repair and the instructor said that when the shaft is spinning at high speed the vanes will flip into the correct alignment even if they were not installed correctly. I'm not sure if that is true or not.

I had 2 more thoughts. 1 - maybe the bottom water pump plate was installed upside down 2 - an obstruction in the water inlet, maybe pull the inlet screens and flush from the top. Just a couple of thoughts that wouldn't take much to check. Impeller rotation should be clockwise.

peeing on the muffs doesn't necessarily mean a lot, my engine pees even if not running when on muffs

I'm aware of that, which is why I pulled the foot off. Everything Looks fine so i am back where i started.

Make double sure the pump is installed with correct rotation. I have seen them where they won't flip. Just had one on a guys motor last summer he put in backwards and didn't flip.

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Originally Posted by wannabe fisherman

peeing on the muffs doesn't necessarily mean a lot, my engine pees even if not running when on muffs

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It should because the water is under pressure from the hose and not the pump. A lot of people tend to turn the pressure up way too high when running on muffs and makes it appear the pump is working correctly.

What about the thermostat? Doesn't it have to be open for it to pee?

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Originally Posted by fishingman

What about the thermostat? Doesn't it have to be open for it to pee?

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I don't think so. As I understand it, the tell tale hole bypasses the thermostat and just indicates the pump is working. The main water discharge from the block comes out the exhaust port on the back of the motor, I believe.

I would check the pump vanes to see if they are the correct width to fill the cup. It may have the wrong impeller installed. Or it could be the wrong diameter.
New pump maybe wrong one.
The only other thing I can think of is the water tube being cracked or bad seal.
Hope this helps.

I had picked up an oem impeller from the Yamaha dealer on the way home when the pump wouldn't work. The one installed looked new, but I decided to replace it with the oem one. May be my imagination, but the oem one seemed to fit tighter in the housing. To insure the veins were oriented correctly I put the impeller in the housing first then slid the housing over the shaft. I rotated the shaft so the key would align with the slot on the impeller and it slid right on. Don't know why I never thought to do it that way before. Takes the guess work out of the vanes orientation.I
I'll try it out shortly but it should work.

Not sure what the issue was but the OEM impeller did the trick.

Attachment 286782

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Originally Posted by SeaRay

Not sure what the issue was but the OEM impeller did the trick.

Attachment 286782

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Good to hear that [emoji1303]


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