when it wont flow water, try bumping the starter, without starting it and see if water comes out, just to move the pump a bit

Would it do that consistently or just some time.
Mine burns the impeller instantly at idle.
The hose/drive is brand new.

What do you lube the new impeller with and what direction do you put the vanes in when you install ?

a dry impeller is toast in 20 seconds or less.i use white lithium grease or dish soap for initial start it sounds like you might have a pinhole or a crack in one of the hoses or a loose clamp somewhere in the system.it is a lot easier to suck air than water.when the drive was installed did you use a new o ring and did you use bellows adhesive to hold it in place?without the o ring it will suck air.

A small bit of dish soap.

I put the impeller in the housing and use a spare pump shaft to turn the impeller and flip the vanes in the correct direction before installing the impellor and housing
on the shaft in the boat. The rotation arrows are on the housing.
I have enough room that I don't need to pull the whole assembly to do the repair.

[QUOTE=mike tkach;4474284]a dry impeller is toast in 20 seconds or less.i use white lithium grease or dish soap for initial start it sounds like you might have a pinhole or a crack in one of the hoses or a loose clamp somewhere in the system.it is a lot easier to suck air than water.when the drive was installed did you use a new o ring and did you use bellows adhesive to hold it in place?without the o ring it will suck air.[/QUOTE

The drive and transom were professionally installed at my dealer.

I had the same impellor issue with the old drive.

When I install a new impeller it always gets it's prime right away and works fine.
It fails after sitting for a while or after being towed to a launch.

This is why I am thinking it's an air lock issue,

Don't do this 'prelaunch start up' routine you have, and just start it when dunked. See if this changes the life of the impellar.

I can't tell you how many people have issues with the Bravo set up on the trailer but totally fine when in the water.

I know what you mean but it has failed twice in the water.
I launch it, get under way, at low speed both times and a few minutes later, the temp alarm is beeping and steam coming out of the exhaust.
I carry a kit with me, and fix it on the spot, takes about 45 minutes and is a pita next to a hot manifold.
Again, works fine with a new impeller and I enjoy the rest of the day.

https://www.gcsmarine.com/content/impellers/impellers

maybe this would at least help you to identify the location of the cause without having to stop and change out another impellor

Consistently and it was right after a brand new transom assemble was installed by a dealer. Triple check it