1969 Mercury 650 - Odd Wiring and Solenoid Question

[rusty_shackelford]

I have a Mercury 650 Thunderbolt 4-cylinder. The serial number (2504342) tells me that it was made early in 1969.

The wiring in the motor has been jacked up by at least two different "mechanics" over the years. Instead of replacing the crumbling wiring harness, they just drilled holes in the side and ran their own wires (old trailer wiring) to various components. I've decided to replace all the crazy wiring with a new proper wiring harness.

The first issue is that the motor components don't match the schematic. THIS the wiring diagram (http://www.maxrules.com/oldmercs/Wiring/1966ona/30.gif) for my motor, but THIS ONE (http://www.maxrules.com/oldmercs/Wiring/1966ona/26A.jpg) actually matches the components inside the case almost identically.

So I went with the wiring diagram that matches the components. That brings me to the solenoid. There was an aftermarket (Hitachi 104-136) solenoid wire tied in place. The Hitachi has no markings on it. Just a yellow wire and a black wire and the much larger 12v terminals. The yellow wire was attached to the starter switch and the black wire was screwed to ground. I got a proper solenoid, but I'm not sure how to wire the terminals. The 12v+ terminals are easy enough to figure out, but does the yellow wire from the ignition switch go to the "S" terminal or the "I" terminal? And should the other terminal go to ground or just not be used, which appears to be the case in the 26A wiring diagram that seems to match my motor?

I hope I made this clear enough. I'll answer any questions ASAP. My big fear is that I'll cause a fire or worse... have to buy another $115 wiring harness!

Many thanks for any advice given!

 

[GA_Boater]

Welcome aboard.

Did you buy the new solenoid at an auto parts store? Sounds like you got a Ford solenoid. Yellow to "S".

 

[rusty_shackelford]

Actually, I got the solenoid from Amazon. It's aftermarket, but it's supposed to be a replacement for the original part number. So what about the "I" terminal? Just leave it unconnected or should it go to ground?

Also, since the Hitachi solenoid was just wire-tied to something, I have no idea where this solenoid is supposed to attach. I think it bolts near the coil. Would you have any idea if that's correct?

Below is a photo of the area I'm talking about. You can see some of the cobbled-up wiring and where the old solenoid was wire-tied below the starter. The red arrows are where I think the solenoid is supposed to bolt. Any ideas?

 

[wrench 3]

Do not ground the I terminal!

 

[merc850]

Does that solenoid have a curved mounting bracket, if so it bolts to the starter case - if it has a flat base there should be 2 threaded cast bosses in the lower cowling; you can use this method for deciding what terminal goes where because there are 2 types. The "magneto analyzer" is a VOM.

 

[rusty_shackelford]

All good info, thanks! The replacement solenoid has a flat base and fits nicely on the screw bosses with a couple of 1/4" x 28 3/4" long bolts. Everything solenoid/starter wise works well now and she'll crank over endlessly, but just won't start. I think it might not be getting fuel to the cylinders. I'll have some time this weekend to work on it and post any questions in a new thread. Thanks for all the info and the manual page!

 

[coondoggyjr05]

Rusty,

Was there any update on this?

I inherited a Merc 650 that I'm struggling to get working properly. After cleaning the carbs and putting back together, we took it out to the lake and it started up like a dream. It idled perfectly. It would go into gear no problem. But would not move us forward. I'm a total noob when it comes to motors, but there appeared to be a "Y" part that I'm guessing opens the carbs to let fuel into them, that was positioned in the middle of the, what I call, timing advance body. When accellerating, this thing rotates outward, but it was not grabbing/moving the "Y" that I assume opens the carbs up. I positioned that "Y" between the timing advance body and now when I hit the accelerator up front, it moves and also moves the "Y" with it. This is how I believe it to work, but for some reason now it won't start at all. Starter picks up, but there is nothing now. Why, if the timing is correct, would it all of a sudden not start at all?

Thanks all! This is my first post and I'm hoping to get this old relic working before the hunting season!

I appreciate anyone's advice.

Maybe I should start my own thread on this topic?

Thanks again!

 

[GA_Boater]

You answered your own question.

Off topic and closed.