Ventilation & Trim Gauge

[richz3]

I have a 2018 24SSRXC with a Yamaha F150. Bought it new 8 years ago and just did the 100 hour service last year -- so limited use. The trim sender arm was stuck, and the trim gauge didn't work, so I had my service guy spray some WD40 on it to free it up. He said he made an adjustment too, while he was in there, although I'm not sure what he adjusted. I just took the boat out and the gauge is working fine but I have to have the trim in the full down position to run the boat. If I raise the trim slightly (when I get on plane) I get severe ventilation...like giving the car a lot of gas when you're on ice...RPM's surge but the prop is not gripping the water. Lower the trim fully, and the boat seems to run fine. I asked the mechanic what he adjusted and now he says he doesn't remember. Anybody have any ideas what he might have screwed up? For 8 years, I have started with the trim fully lowered, then brought the trim to level when at plane, and the boat ran like a champ. Now, the trim has to be fully lowered or else I get severe ventilation...can't even get moving unless the trim is fully lowered. Would love to get it back to where it was! Does anyone know what adjustment he could have made to cause this problem?

 

[DVW]

The adjustment is made on the very same sensor that was freed up. The sensor is mounted on the motor tilt pivot. Based on your description of the problem this may not be a do it yourself project.