I was running the boat on the hose today and before I fired it up I noticed that water was passing through the exhaust before I cranked it. Never done that before...only flowed when it was cranked. Only thing that I can think of is the hose at the house has a lot of pressure! I usually run it at the shop where the pressure is mediocre. Should this through any red flags or is it just the high pressure of the hose?

weak, bad/torn impeller, allowing water to pass by.

Many manuals say not to start your engine until you see a little water coming out the exhaust. My engines take quite a while before they fill up on the hose. You don't want to start the engine too soon.

x2

Sometimes if the impeller lines up just right in the pump housing, it will do this. Even with a new impeller.

x-2 but would still check impeller

Agreed, I will not start my motors on the hose until I see water flow out the exhaust!
Takes awhile, but I know that there is enough water flow to run!

Question: Is it possible to just pull the suction hose off the back of the impeller and feed a boroscope through the opening to check the vanes on the impeller? Seems like that would be much easier than pulling the pump off to inspect. I got a boroscope for Father's Day, and am just looking for new ways to play with it.