Trim Question

[Jilda]

New to boating and have a 50HP Mercury 4stroke BigFoot 2004 on a 20 ft pontoon boat. When I am going forward I can trim the motor up and down fine. When I increase the throttle the motor seems to sink slowly to a straight up and down position. When I back off the throttle I can trim up again. Is this normal? I have check the manual adjustment screw and it is still tight. I am on a lake with lots of weeds. I have checked to see if there are any weeds dragging but that doesn't seem to be the problem. This causes a problem for me because there are shallow parts in the lake and if I'm trimed totally upright it's not good for the lower unit.

 

[DJ]

Re: Trim Question

Jilda,<br /><br />Is it possible that your trim pin is in the outermost (toward back of boat) hole already? If so, you are working the tilt only portion of the power tilt and trim, and not the trim.<br /><br />The tilt will not allow running at speeds much above an idle.

 

[BillP]

Re: Trim Question

Are you talking idle speed only? My 50hp 4S merc clone (mariner) says a limiter kicks it down when the speed reaches 2000 rpms. Mine actually kicks down at 1500rpm. The motor has to be tilted way high before this works...you blowout the prop at high speeds before this feature rears it's ugly head.

 

[Jilda]

Re: Trim Question

I'm sure both of you will just shake your heads at this answer but I'm really trying to learn. I don't know exactly "what" I'm talking. In my terms I push the up/down button located on my throttle to get the motor to tilt up/down (in/out) of the water. I will be going along just fine with the engine cooling properly so I know it's in the water far enough. When I push the throttle down and go faster the motor sinks to a straight up/down position. I don't have a gauge to check RPMs. BTW - what does it mean to blowout the prop at high speeds.

 

[BillP]

Re: Trim Question

Ok, if you are going along at the slowest speed with the motor trimmed high...the trim will automatically lower when you advance the throttle past 2000 rpms. Your motor manual should tell you about this...mine does anyway.<br /><br />Blowout is when the engine is trimmed too high and the prop sucks air...not a big issue at idle speed but at high speed it can over rev the engine.

 

[Spidybot]

Re: Trim Question

It is important to note the difference between TRIM and TILT.<br /><br />When the motor is all down (trimmed in until the motor is stopped by the tilt pin, placed in one of the holes on the bracket outside) and you push the button up, the trim will force the motor out. This is meant for use under all running conditions and will keep also above 2000 rpm. The purpose is (among others) to lift the bow (front) of the hull.<br /><br />If you keep the button lifted beyond the trim range, the TILT takes over. Tilt is meant for tilting the lower unit out of the water. Purpose is to keep it clear of objects (when beaching or trailering). The tilt position is not meant for running except at very low rpm (shallow waters) and will give if you add throttle. In this position the prop works very ineffectively thus leaving you with only a little steering ability.<br /><br />On most models you notice a slight change in operation when going from trim to tilt, as tilt operates somewhat faster.<br /><br />If your motor cant keep in a trim position, your trim system is defective.

 

[rickdb1boat]

Re: Trim Question

And don't forget to check the T&T fluid. Also, when on the trailer, see if you can push the lower unit down by hand when it's tilted up without touching the T&T button. Let us know...

 

[Formula1974]

Re: Trim Question

I have asked this before but cant seem to find the post but what happens if you can push the unit down with your hand? Is the tilt/trim shot?

 

[Jilda]

Re: Trim Question

Thanks! Your answers have been most helpful. I need to check the fluid and will let you know what I find out.