TOPIC: MerControl not working - 1964 Mercury 500

I have a new to me 1964 Mercury 500 on a Fabuglass Fury 142.

This engine is in great shape with very low hours on it. I had a local boat mechanic replace the water pump and the motor runs awesome. He checked plugs and other parts and adjusted the carbs. Engine runs very smooth and is surprisingly quite. Challenge seems to be in the controller. It will not throttle up in forward gear. There seems to be a lot of play once you shift into forward and the handle moves all the way down, but no power. While the lever is all the way down, the engine is only at a low RPM. It feels like it should go down more, but it is all the way forward. In reverse, it has full power just like you would expect. I can feel the tension on the cable as I move the lever in reverse. Yesterday I took it out briefly and after going from neutral to forward a few times, it seemed to grab and I had full forward power. The lever had a very different feel that time. There was no play like before. I stopped for a minute and trying forward again. Did the same thing, no forward power. Lever goes down, but does not grab and rev up the engine. A few back and forth movements and it grabbed again and I had full power.

At home, I took off the cover and can see the distributor unit rotate when in reverse, but it barely moves in forward. The lever had the same play in the forward action. I can push it down fully, but can tell it is not pulling the cable properly at the motor end.

Oh, forgot to mention… the other small throttle lever, moved up when I pushed the main lever all the way forward when it did not engage. The times the forward lever did engage the engine, the smaller lever did not raise up on full forward throttle

I had done some research and it seems like these control units are tricky. I see lots of online posts of people with the same issue. They take their controller apart thinking they can fix it and cannot get it back together.

So before I do anything, I would appreciate any thoughts you have.

I posted a short video of this on YouTube. Not sure if the link will work on this forum. If not, go to YouTube and search for my vides. In the search box, type in bonesdc1895 This is the only video I have !!



Thanks,

Joe Foley
Salem, VA

call me 1 914 310 7086. Dave.

Hi Dave,

Nice talking with you last night. I tried what you suggested. I held down the fast idle lever and pushed the throttle lever all the way forward. It would not go. I pushed very firmly, but did not want to force it and break anything. The main lever only moves forward full if the fast idle lever is allowed to rise up.

Joe

Hi,
I would suggest you buy a Merc repair manual as it covers controls too and the pictures for cable replacement with the control split apart help line everything up for correct reassembly.
It also covers correct cable adjustment at the motor end. It is not hard to do but, without all the instructions in the manual it is a guessing game to reassemble right. The fact that the halves go together is no guarantee everyting is in the right place.
A few things come to mind that could be wrong: The rack gear connected to the throttle cable is not in the correct position relative to the sector gear moved by the throttle lever. There are allignment features on all the gears to do this correctly before sandwiching the halves together.
It is also possible you have broken a tooth, sometimes catching the adjacent tooth and then it works OK when it doesn't catch it doesn't work. Or one of the hub bushings is gone, (they are those plastic split bushings) that would explain the looseness and would also cause some gear engagement issues.
The cables cannot be connected to the motor when setting up a control assembly. The cables wind up where they do as the barrels on the cables on the control end are fixed. Once the control is reassembled and mounted to the boat the cables are then adjusted to fit at the motor end where the barrels are adjustable.
Good luck,
Randy

Hi Randy,

Thanks for the suggestion. I would feel much more comfortable working on this with a drawing or manual. I have found a Mercury Boat Motor Service Repair Handbook 50 to 150 Hp 1964-1975. Since mine is a 1964 mercury 500 50 HP. That sound correct?

Joe

Common problem. The cam inside the box is worn, the heart shaped one. Unfortunately the only fix is a new one but they are NLA at the dealers unless you can find a leftover on a dealers shelf somewhere. To assemble the box without cursing, pull the black lever about half way up as you offer the sides together and it will pop together without difficulty. They are a nice box when working right.

Took it apart today and looked it over. No obvious worm parts. Greased it all up and put it back together. Same issue AGHHHHH. Took it apart again and noticed the grear shifting section had a little bit of play to the interconnecting mechanisms. It seems to rock some. The small spacer on the left half that the handle attaches to seemed to allow a little play there. I put on a very thin bushing that fit over the handle connection hub. This took out the little play. Put it back together and it works fine. I must say it is very tight and hard to push the lever, but it works!! I am hoping once the grease gets all worked in it will loosen up some. I suspect the cable may be the source of the tightness.

THANKS

Joe

most likely.