Water pump not pumping up to engine

Hello.
I have a Tohatsu 55hp M55B that I have had in the water once. I was suspicious that the water pump was a bit average to after six months of sitting around, I dropped the bottom half and replaced the impeller (two fins missing and I found the fins). Anyway, to cut a long story short, I could not get water out of the tell tale. I took the pump off again and I now have the garden hose connected to the pipe that goes straight up to the moter form the pump. I can turn the hose pipe on full and it builds up enough pressure to blow the hose pipe off before any water gets up to the engine. I have removed the thermostat and the side plate that the temp gauge and tell tale pipe is connected to and no water in these areas. Is there some sort of filter or shut off valve at the top of the pipe from the water pump? I can faintly hear gurgling sounds from the plate where the tell tale was if I pull the hose pipe off the bottom pipe and put it back on again. I would of thought that I would get water gushing out the top of the engine if I have mains water pressure pumping up the pipe from the pump.
Any ideas would be greatly appreciated.
Best regards,
Scott.

That's a real museum piece. Was it pumping before you replaced the impeller? There isn't any sort of filter or shutoff, but a chunk of crud or a mud dobber's nest could block off the water line.

Yeah! It's an oldie but she's still chugging along
It was pumping in dribs and drabs before I set it aside for a while. After coming back to it and replacing the impeller, I have no water flow. I was reasonably confident in the pump unit but to be sure, I fit a garden hose over the pipe where the pump usually connects to the motor. So now I know I have plenty of pressure shooting water up the inlet pipe, but nothing getting to the thermostat. I had read about the trusty mud dobbers nest so I pocked a piece of wire up the hole but I'm not getting any mud on the end of the wire when I pull it out. I'm also getting a metallic sound when I stick it in all the way like its hitting a metal plate or maybe a corner? I just tried again with the hose up the inlet pipe and I can hear a small gurgle of water through a hole in the engine where I removed the tell tale pipe. The water sounds pretty close and I swear I can hear a metallic click as if there was a clacker valve in there. Am I going to have to remove the bottom half of the engine? I have the gearbox off but I have not got the shaft off yet (I think that’s what it’s called, I'm waiting on a manual).
Thanks very much for the reply Paul.
All the best,
Scott.

It feels like the blockage is up where the drive shaft housing meets the base of the engine.
Are there any special tips on dropping the drive shaft housing? I am thinking that this might give me a better view of where the blockage might be as I can’t get to it from the water pump or from the top.
Does this sound like an appropriate course of action?
Scott.

Problem diagnosed.
The aluminium pipe that leads from the water pump up to the motor has corroded in three places. I would say the boat was sold to me like this. There was new goop around the corrosion and that made the water pump when I bought it. The top of the pipe was so corroded the rubber bung had amalgamated with the corrosion to make a great big blob of chalk and rubber. The engine is now sitting in three major pieces and bits and pieces around the floor. Fortunately I have some lengths of pipe to suit and a pipe bender so all I have to do is get/make some grommets and make new gaskets. I would say a day and it should be back together and firing up Fortunately, during disassembly, I found a few other things wrong with it due to either poor maintenance or age so I can recast a load of parts in urethane and she will be as good as new.

You are probably striking the motor base. There isn't any elbow in the water pipe on that model that I know of -- just a jog to align the pipe with the motor on top, and water pump on bottom. On occasion, we will use compressed air to clear a telltale port; You could probably also blow air into the thermostat cavity. Yes, a lot would go out the water exhaust, but pressurizing the cooling system might blow whatever blockage back down the water pipe. To do that, you will need a good supply of shop air, not just a tire-filling 12v compressor. If you still can't get cooling system flow, you will probably be pulling the powerhead, and possibly pulling the side covers off of the block. Make sure you are prepared to replace the base gasket, as I'm not sure that a Factory gasket is still available.

Thanks for that reply Paul.
Unfortunately, I think we must have been writing our mails at the same time
I did end up pulling the power head off. I tried blowing 60psi of air into the thermostat cavity first but nothing seamed to work. That’s when I pulled the pin and decided to learn a bit more about my engine. I bought some gasket sheet today so I'll be cutting that out tonight.
I can't thank you enough for taking the time to offer your expert advice. I really appreciate it.
All the best,
Scott.