Trim Gauge ?

CaptianMark

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2017 F40 Yamaha on a SL16, 420 hours. Trim gauge stopped working so my local dealer gave me a new one. I replaced it and now the new gauge reads only from 1/2 and up. Before I start fooling with the sender is it possible they gave me a wrong gauge.
 
Thanks Little B. Have had the same problem
 
Don't know if this is relevant, but I have found that my trim gauge will not be accurate when I first launch the boat, then within a few minutes it will start to reflect true trim. Our boat is stored on a trailer and the gauge will be dry for weeks (or months).

A couple of months ago, I spent quite a bit of time figuring out the adjustment process and getting it just right (in the drive-way). The next time we launched, it seemed initially to be stuck on the trailer setting (full up) even though I obviously had it down. Within minutes, as I adjusted trim, it started to respond. After a short period, it was almost as accurate as my original adjustment. This happens consistently.
 
Yesterday I found my new gauge to be good, my boat did require an adjustment to the arm that works the sending unit. The sending unit is a plastic unit mounted to the motor. It has a plastic arm that pivots as the motor moves up or down. This plastic arm moves as it reacts to a metal arm fixed on a horizontal shaft. The position of this metal arm can be adjusted and this will adjust the gauge. This is some what sensitive thus a small movement of the metal arm will cause a large move in the gauge. I do have one question, how do you find dead center on the gauge? What position should the motor be in to read center?
 
I think the only absolute position you can measure is all the way down. All other positions are relative to that. Half way up physically with the motor may not read half on the gauge. It doesn’t matter since the gauge is just there for you to be able to repeat a certain setting. Doesn’t matter if it reads 1/2 or 3/4 in the grand scheme of things.

Having the motor and gauge synched at the all the way down position will , I think , give you the widest useable range on the gauge. Anything more than that is overthinking things in my opinion.

And yes , they can be touchy. Easier to do with two people for sure! Mine was reading 1/4 trim when all the way down and after several adjustments it’s within a couple needle widths so I’m calling it close enough.
 
The Final Solution. I went out on 11/12 and set the tilt on the motor for maximum performance. I stopped at a sand bar, shut the motor off, and walked around to the back of the boat. I adjusted the sensor arm to read dead neutral with my wife in the captains seat since I could not see it from my position. The gauge now reads correct. With the motor all the way down, it reads all the way down on the gauge. The center of the gauge indicates maximum performance.
 
The Final Solution. I went out on 11/12 and set the tilt on the motor for maximum performance. I stopped at a sand bar, shut the motor off, and walked around to the back of the boat. I adjusted the sensor arm to read dead neutral with my wife in the captains seat since I could not see it from my position. The gauge now reads correct. With the motor all the way down, it reads all the way down on the gauge. The center of the gauge indicates maximum performance.
Good show! There is no set or required calibration for our trim systems. Use/set it the way that works for you. I used a similar process to set the "trailer stop" on our Mercruiser that operates by a similar sensor. That stop is intended to avoid over trimming while underway. I use it to nail the trim for max speed without looking at the trim gauge. Lifting the drive to higher angles still works the same way.
 
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