My boat was only two years old when the impeller when out last week. I had to replace it the day before a week long trip to LOTO

. Paul, it was a PITA. First, remove the engine.... then remove the impeller on the bottom of the engine..... Then call EVERY PLACE in KC until you can find a replacement!
OK, venting complete.... I just got back from the LOTO, and had a good time. Boat did well over many many miles of WOT operation. We went everywhere between the 47 and the 81 mm! Lots of time tickling 50 mph... not too bad for the 5 blade prop.
This is what I did....
To replace the impeller I went in from the front. I have two removable panels. One in front, the other on the stbd side of the engine. I removed both for access (it doesn't look like you have that prob). Next, remove the belt paying carefull attention to routing. Remove the large hose between the engine mounted H2O pump and the T-stat. Remove the pulley above the raw water pump. This give you access to un-bolt the fuel filter. Diusconnect the fuel hose closest to the front of the engine, the vent hose, and the wire harness also on top of the fuel filter (far left hand bottom of your pic). Un-bolt the filter (two on one side, one in back), remove the mounting bracket from the engine.
This gives you good access for the impeller and hoses. At this point mark and remove the two hoses in back of the impeller, and remove, pulling it forward. The rest will be specific to your make/model.
To install, reverse above. I hope that helps!
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Walt B
"Debt-Charged"Black '07 H210SS6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.