1999 Mercury 30 hp 2 stroke won't pump water

jimbo61

Recruit
Joined
Apr 28, 2013
Messages
2
Recently took the cover off the boat,and began getting ready for the season.Hooked up the garden hose and fired up the engine.No water was coming from the telltale,and while it was still running,gave it a little squirt of compressed air,to hopefully clear any obstruction.Still no flow.Shut off the engine,and decided to dig a little deeper.Checked the hoses and found them clear.Re-started the engine and still no flow.As I have only owned the engine for one previous season,I never changed the waterpump,though it worked well last year.I figured it was time to do so_Ordered the kit and replaced the pump.The one that was in there looked like it should have been pumping water.The vanes were permanently curved,but none were missing,and the base plate was slightly scored from sand damage I would guess.The silicone gasket between the pump and exhaust was like new,and the rubber pick-up tube,tho like new,was replaced with the one from the new kit.Re-assembled everything,fired it up,and voila! NO FLOW!.Dis-assembled it,just to make sure I didn't screw up the key,or orient the vanes wrong.Nope,all was fine,so put it all back together.When I went to start the motor,I had forgotten to hook up the gas line,which I was using on another boat,so I was turning the engine over with the battery,and water was pumping out the telltale nicely.Problem solved! WRONG! I hooked up the fuel line,and as soon as the engine fired over,the water stopped coming from the telltale.I let it run for a bit,and it was beginning to get hot,so I shut it off.I pulled the safety lanyard and turned it over with the battery,and water once again shot from the telltale.I am at a loss.I even spoke to the local Mercury mechanic about it and all he could suggest was to re-check the pump installation.It made no sense to me to check it if it pumps when the battery is turning it instead of compression,but I did so,and once again found no issue.I even took it apart again and oriented the vanes the other way,just for something to try.As I said,I am at a loss.Anyone ever have this problem? I even tried blocking the water intake forward of the steering skeg with duct tape to restrict the water from the ears from escaping that way.No difference.The fact that it pumps beautifully under battery power makes me think that somehow exhaust back pressure is causing this.Perhaps a blown gasket somewhere? The Mercury guy said that was highly unlikely,but I'm beginning to wonder.Any help or ideas would be greatly appreciated.Thanks in advance
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: 1999 Mercury 30 hp 2 stroke won't pump water

Do your plug electrodes look the same?
Sounds like its getting pressure in the water system to me.
Have you done a compression test?
 

jimbo61

Recruit
Joined
Apr 28, 2013
Messages
2
Re: 1999 Mercury 30 hp 2 stroke won't pump water

Do your plug electrodes look the same?
Sounds like its getting pressure in the water system to me.
Have you done a compression test?

The compression is low,but was when I purchased it last year.The spark plugs look normal,no signs of water.I'm thinking the water jacket is breached somewhere as well.
 
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