trim gauge issues

**jflan224** · 11-04-2025, 02:19 PM

1987 merc 200 hp outboard when motor is all the way up the gauge reads all the way up . when i trim down the gauge comes down as well , when it comes off of trailer mode the gauge is all the way down, when i continue to trim all the way down the gauge comes back up to half way . so when i trim back up from all the way down the gauge is moving down untill i hit trailer mode again then the gauge starts to come back up ! whats the deal am i missing something tried multiple sensors and gauges all do the same thing ! do i need to move the rod that the sensor locates on ?

**mercrazy** · 11-04-2025, 02:32 PM

Is your trilobe pin sheared?

**jflan224** · 11-04-2025, 04:44 PM

i dont think so . that is the pin that takes over for trailer mode correct ? i thought maybe that pin needed to be tuned but it is tight. i mean i stuck a big screw driver in the slot where the sensor locates and i could not turn it ? i think we are talking about the same pin ? update i watched a video on the trilobe pin removal and i understand what you are talking about now, i will have to check it out but like i said earlier i would think that if the trilobe pin retainer was broken i would think think that the rod that the pin holds would be able to turn in its housing no ?

**mercrazy** · 11-05-2025, 07:44 AM

It would be very hard to turn the pin with engine weight on it. Have someone hold up on engine while you try to turn it. If the trilobe is sheared it will still be hard to turn. With the sender removed, watch the slot as you trim up and down as far as you can see it. Turn the sender by hand to see if it acts right on the gauge. If the trilobe isn’t broken, I would try a different sender.

**Glastron1987** · 11-05-2025, 08:02 AM

I've never found those senders to be the most durable Mercury part, but they are expensive.

**jflan224** · 11-05-2025, 08:38 AM

the sender is brand new and it acts the same as
my old one, tried them both and also new gauge they all give same result. im going to look into the trilobe pin deal today

**Glastron1987** · 11-05-2025, 09:09 AM

Originally Posted by jflan224

the sender is brand new and it acts the same as
my old one, tried them both and also new gauge they all give same result. im going to look into the trilobe pin deal today

That makes sense then. Good luck.

**skialot2** · 11-05-2025, 10:57 AM

Just an FYI. The slot in the cross pin lines up with the trilobe pin. If its not lined up the trilobe pin is broken. To fix it the motor has to come off the boat.