1978 500 Mercury bad switchbox and more?

[supreme]

Hello everyone, I have a 50 hp 1978 Mercury # 4964296. I bought the motor because it has great compression around 140 on all but all the wiring looks bad. So I am going to replace wiring and some ignition parts need be. I am playing around with my Ohm meter on the switchbox, I noticed that when touching one probe on the housing or a ground and the other on all of the coil terminals of the switchbox the buzzer goes off. I think it's bad right? Another thing it looked like the rectifier was hooked up wrong. It has three terminals one has two positive marks on it with one terminal between and the other two are on the other side with no markings. Does the positive wire coming from the ignition (red wire) go to the one marked positive terminal? And the others ( yellow ones) go to the other two terminals? If anyone can help it would be great thanks.

Many Thanks
San Diego
Devin

 

[flatcat77]

Re: 1978 500 Mercury bad switchbox and more?

it might not be bad. hook some gas up to that bad boy and see if she fires off.
use a pull rope or make yourself a bump starter using a socket on top of the crank. give each carb a squirt of fresh gas. see if it turns over. then go from there. keep us posted.

 

[supreme]

Re: 1978 500 Mercury bad switchbox and more?

I am not getting any spark at all. Is that the right way for the rectifier to be hooked up?

Devin

 

[flatcat77]

Re: 1978 500 Mercury bad switchbox and more?

that sounds like how my 500 is hooked up.

 

[supreme]

Re: 1978 500 Mercury bad switchbox and more?

Can anyone help? Is this a clear case that the switch box is bad, by having continuity between the coil terminals and the switch box housing?

Thanks
Devin

 

[supreme]

Re: 1978 500 Mercury Timing?

Re: 1978 500 Mercury Timing?

Hey everyone, I install a new trigger and switchbox. I am getting great spark now. I went threw the carbs, I still can't get it to start. I get a single pop out of it. So I thinking it may be the timing. When I placed the flywheel back on I made sure that I line the timing mark to the pointer and TBC. Now when I place the timing light on it and turn it over it doesn't come into the mark at all. It comes in about a 1/4 turn rotation of the flywheel retarded and when I place the timing light on the 4th cylinder it reads close to TBC. Did I wire the switch box wrong or what? I replaced the trigger and the wires are a little different. They did not have a black and white one, it was just black. So I placed it on the black and white terminal on the switch box. Is that right? If someone haves some thoughts on this please let me know. Many thanks

San Diego
Devin