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  1. #1
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    150 four stroke trim stop

    Is there anyway to disable this? I have been driving boats for 20 years and know when to stop trimming my motor. I don't want the boat telling me how much I'm allowed to tim up. I have the single trim cylinder too so it's just in the wiring that stops it.

    My gauge was reading off when trimmed all the way down so I tried moving the sender around a little bit to see if that would fix the gauge and allow me to trim it up more while on plane. Now it trims less and I lost 5 mph and 350 rpm.

    The boat always ran best at max up trim and if I even slightly trimmed down it lost major speed and handling. I would love to trim up a little more to try and get the bow up more, because I feel it dragging the front, and way worse now after it doesn't trim up as far anymore.

    Or does anyone have the wiring diagram for this so i can figure it out?

    2015 trx189 2015 mercury four stroke 150

    thanks

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    #2
    Quote Originally Posted by gonefishin1012 View Post
    .. I don't want the boat telling me how much I'm allowed to tim up..
    Then fix the boat.

    Mess with the motor and you can kiss your Merc warranty goodbye.

  4. #3
    Normally the sender is adjusted so that when the motor is trimmed fully down the gauge indicates fully down. If the sender is adjusted properly then when the gauge indicates the motor is at the top of the trim range the motor will be at the top of the trim range. Which according to the Mercury Owner's manual is 20 degrees Up from being fully down.

    I see that your model motor is limited so that it will not go into the tilt mode (beyond 20 degrees Up) when the motor is running much beyond a fast idle speed. I am guessing that the limit is set by the motor recognizing the sender position but this is just a guess on my part. If my guess is correct then you can "fool" the motor into thinking it is fully down when it actually is not. Trim the motor a few degrees up from its lowest setting and then adjust the sender to the full down position. Then try the motor and see what happens.

    Or you can install a wedge between the transom and the motor so that the motor is at a different (greater) angle to the boat than it would otherwise be. The trim gauge will then correlate correctly with the motor but the motor will have a greater Up trim capability with respect to the boat.

    http://thmarine.com/reverse-transom-wedge.html


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    #4
    I thought about the wedges. Just didn't want to pull it out of the water. I keep it in a slip on a lift.

    No matter how much I messed with the sender it won't read fully down.

    I don't care about the warranty. It's out in a couple months anyway. I'm going to be sending the ecu for tuning after I get this fixed too. Just wanted this fixed.

  6. #5
    I just went to the parts book. Your model uses a trim limit module. I don't have a Mercury Service Manual and therefore can't determine if the module is adjustable or not. I suspect that Mercury does not want it messed with. I also suspect that the trim gauge gets its information from the limit module but maybe not.

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    #6
    Thank you everyone for your input. I really want to completely disable this. I got it back to within 1mph of what it was. I just really want to figure out how to get rid of this. A wiring diagram or a wire that controls this would be great. Again I don't care about warranty.
    Thanks

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #7
    Please see the Forum Announcements, and be sure to provide the REQUIRED info when posting. Thanks!

    A couple of very important pointers:

    -This engine uses a DIGITAL trim sender. It's adjustment should not be altered, as it can cause malfunctions and substantial loss of performance.

    -TRIM angle (maximum) is PCM Controlled. This is hard-coded programming, and if you attempt to accelerate beyond approximately 2500 RPM's (or trim beyond the max position), Engine Guardian will occur. This is a SAFETY measure. Have an Authorized Mercury Dealer verify that you are achieving the maximum 20 degrees of trim angle.

    -A "Trim Limit" kit is also available to install. This is actually a TILT limit kit (designed to stop the engine trim at a fixed position, so as to prevent contact with other objects that might damage the engine).

    -Transom Wedges are not acceptable for use (per Mercury Service Bulletins).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 40 years (learn something new every day).
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    #8
    Listen to DON motors are too expensive to replace,

  10. Member
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    #9
    Thank you for the replies. I'll verify if it's going to 20 degrees or not.

    Honestly I don't care about any warranty.

    My boat actually doesn't plane off trimmed down as good as at halfway trimmed up. I never have a reason to trim it all the way down because of this. I really want about 4-6 degrees more up trim.

    What's the problem with transome wedges?

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    #10
    Don,

    Pardon my ignorance, but if the OP has the Mercmonitor, could this simply be a trim calibration issue? I know the manuals walk the owners through it, but I am not sure if that would affect actual trim or just indicated trim?
    Last edited by cfm56doc; 01-04-2017 at 11:58 AM.
    2013 Z118 w/Merc 150 4S

  12. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #11
    MercMonitor only calibrates the "displayed" trim (does not alter the PCM or trim sender functionality).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 40 years (learn something new every day).
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  13. Member
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    #12
    Quote Originally Posted by EuropeanAM View Post
    MercMonitor only calibrates the "displayed" trim (does not alter the PCM or trim sender functionality).
    Thank you sir.
    2013 Z118 w/Merc 150 4S

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    #13
    Since this is a 0-5volt sensor is down 0 volts and up 5 volts? If so you should be able to install a resistor in series with the 0-5 signal wire and make the computer see less voltage which would let you trim it further. Should be able to measure the voltage at full trim then play with a handful of resistors and easily get more trim out of it. I'm having the same issue with mine and can test it tonight

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    #14
    I was out in my shop testing voltages. 0 volts is all the way down and it looks to me to be about 1.5volts D.C. is when the trim shuts down. I'm not telling anyone to do this but it sure looks like a resistor can be added in series with the white wire to make it trim higher than it does now. The 3-wire triangular plug on the left side of the motor red +5vdc, black 0vdc, white wire is the variable 0-5vdc. I've got plugs exactly like that in my shop so would be simple to make up one that would fit right in there and also be able to be removed easily.
    Last edited by Northwoodswalleye; 04-23-2017 at 09:12 PM.

  16. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #15
    Interesting thought... but it will also alter the overall voltage range the PCM sees (not just at the trim limit point).

    Additionally, any trim gauge installed will read incorrectly.


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 40 years (learn something new every day).
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    #16
    Yes but in my opinion the trim gauge already reads incorrectly!! Yes the pcm will see a lower voltage only for the trim sensor but all it is doing with that voltage is limiting trim. The 5 volt power for the pcm will be unaffected. I have the male female plugs in my hand if it ever warms up (snow this morning!) I will test and post

  18. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #17
    Limiting trim is not the only thing it does with trim angle. There are FAULTS (and Engine Guardian Strategies) related to TRIM ANGLE.

    If you wish to see more movement on the instrument, consider a Smartcraft Instrument (and a System Link Trim Gauge).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 40 years (learn something new every day).
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  19. Member
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    #18
    If the pcm sees 1.4 volts instead of 1.5 volts it won't change how the engine runs or create a fault. I understand the engine guardian (cut power if you try to run the motor above the normal trim limits) and it will fault if there is an open circuit in the wiring. Changing the voltage that the pcm sees will only make it seem like the motor is trimmed less than it is. I did order from you last week. Thanks very much

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    #19
    Well the snow finally melted enough to get out this afternoon. I ended up using a 47000 ohm resistor in the trim circuit and boat runs fantastic. Can trim up to 1/2 the gauge now. Runs 5800rpm with bravo 1 FS 20p prop and ran 50.6mph gps on fairly flat water. 52 with the wind and 48 into it. Very happy with the 4-blade prop. Supposed to get 6 more inches of snow tomorrow this weather is horrible!

  21. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #20
    While it sounds like you've accomplished what you set out to do, it's very important this be pointed out:

    Please be very careful. Modification of the trim sender signal may allow the engine to achieve more trim, which in turn allows the swivel bracket to travel further OUT of the transom brackets than was designed (reducing the lateral support designed into the midsection).

    This may cause, or contribute to failure of critical midsection components (safety concern).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 40 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

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