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Several time this year on my 1999 200 EFI Merc my motor has trimed up by itself when running at high speeds it happens very slowly Ill hear the engine difference and Ill look down at the trim gauge and it will be 3 or 4 bars higher (BP101 dash) than I was running on fairly smooth water. I know 2years ago the switch on the motor went bad and trimed it right out of the water while running wide open but this is different I dont think it electrical Could if be lack of oil in the Tilt/Trim cly. If so what tye of oil does it hold and how do you check/fill it.
It would almost have to be electrical since that is the only thing that will engage the electric motor that drives the pump. sounds like either a switch problem or you have the blue wire (or blue/white) shorting to a positive wire some where due to vibration. JohnJones Trolling Motor Services870 773 3474Motorguide/MinnKota/PowerPole/Lowrance/Humminbird
Ok I was thinking maybe the cyl was not holding and allowing the engine to come up.. Wasnt sure if that was possible.. Well now I have Four switches to look at and it has only done it several times and I been out a lot also has only done it when running open on fairly smooth water. I might have to wait till it get worse to find it. I replaced the one on the engine 2yrs ago Man that was something running wide open and the engine just trim up all the way .. Flooded the boat when I got off the hot foot and shut the key off. My coangler looked at me like I was crazy lol lol Merc dealer said is was fairly common thing moisture gets into the switch and short it out but I guess always up .
It is usually not the switch on the handle, elminate that one last. It is more frequently the one on the engine. We suggest you take that one out and go to your kitchen table. Separate the switch and see if there is moisture in that switch. It will be apparent and the moisture will be in the case. The moisture will have a stench if it has been a conductor of current and a black look. The contacts on the posts will be burned and marred also. Clean that switch up and if the springs are in good shape you can fill it with petroleum jelly (Vaseline) and reassemble it. Then reinstall the switch. This is probably going to handle your issue just fine and we have done a good many of the switches that are not sealed on the cases. BCB
I can do that, I have 2 switches now, so I think I will look at both and keep one ready and handy for future. No one else in my club has had this problem and we run a lot of merc. Twice for me I guess
surprising no one has ever had a problem with the motor triming up while driving down the road and the transom saver coming off the roller would be an issue when you went to stop. ouch..
two other things to mention:(1) if the cylinder leaks, the motor goes _down_. you have 400-500 pounds of motor that the two cylinders hold up while running, or when you trim all the way out of the water, the center cylinder now holds everything. If it leaks, first floor here we come.(2) Ive seen a few failures of the bow-mounted trim switch if you have one. I burned out a trim pump motor on a new boat back in 1992. Apparently towing home in a monsoon got water into the switch. I left the boat in the driveway until the rain stopped and when I went out, motor was trimmed all the way up. My first question was “who raised the motor?” No responses. I tried to lower it, and _nothing_. When I went to the back, it smelled badly. Eventually found that the front switch had water in it, and apparently as it mixed with the grease used in the switch, it made a conductive concoction that raised the motor and continued to raise it until the pump burned out. Luckily it was a warranty repair.I have see more failures on the cowling switch, next comes the bow switch. The throttle switch seems to be reliable, and the “turn signal” type trim switch has never caused me or anybody I know any problems.You can get a relay on the motor that sticks, but you have to press the button first, but releasing it doesnt stop the pump.2008 Pantera Classic2014 Mercury Pro XS 200
All and all this is making me feel better a switch is an easy fix and a reasonable one. Thanks OldTimer what was I thinking I know the two small ones are there to trim up.. I guess I wasnt thinking lol.. that the boat going forward was pulling the motor up … Ok Motor weight, motor forward power thrust. vs water pushing against the lower end as the boat goes forward.. Yea I needed your wake up call to say like DUH… DUDE.. It electrical whether you like it or not. lol lol Thanks all I will finded it.
main thing is this… get it fixed. If it sticks, it will burn the pump motor up. It isnt _that_ expensive but it isnt a $100 repair either. The switch is cheap. Id replace it if I suspected it was acting up to avoid a much more expensive repair. Another test is to just take the hat off the motor and unplug the cowl switch. I am not sure how yours is wired, but mine has bullet connectors that I can pull out and disable that switch without disabling the other ones. Of course, test before you hit the water or you will look like a newbie driving around with the motor tucked all the way down. 2008 Pantera Classic2014 Mercury Pro XS 200
OT57 is right that the front switch could be an issue, though you should have covers on those and it is rare unless those boots are broken. The Mercury cowling switches can be repaired, and even a few folks at Merc. in Service (which will remain nameless) are following our lead on this after multiple failures on one engine often. BCB
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