1973 mercury 1500 L6 Water Pump Issues

I finally got this engine to start after replacing most of the electrical system. I put it in the tank and started it but no water coming out. I replaced the water pump impeller due to the boat setting up for a while. Before I put the LU back on, I hooked a hose up to the water pipe to make sure I had water flow. Installed the LU and still no water coming out. Removed LU and checked keyway and all is intact. During install, I put a little lithium marine greese on the impeller and turned the shaft clockwise as I installed.

Does anyone have any suggestions?

Is the water in your test tank 8" above the impeller , yes or no ?

It is only covering the bottom vent holes. I did put the muffs on the bottom holes as well, I will try that this evening.
Thanks for the reply

I have seen where water would NOT pass through a new impeller with the muffs--and even with 50 psi water pressure! Drove me batty! Soon as the motor ran awhile it was 'normal' again.

Jeff

I was just concerned that I might overheat the engine if I let it run for too long with no flow.

I filled the tank to the bottom of the tilt cylinder, got a little water after about a minute but it stopped and then all I could get was air. Also, as I give it throttle it does not spin the prop but it will work in reverse.

racerone, did you see my last post?

Took it back apart and used the original housing Don't know why but water pump problem solved.
Re aligned shifter shaft and fixed no forward problem.

going to take it out to the lake next weekend and open it up!