Mercury 650 NO SPARK, im out of options, please help!

[FishHunter007]

I have a 1978 Mercury 650 with no spark. I have exhausted all of my research options and am pleading for help at this point. I have went through the cdi testing procedures and cannot figure this out.

When I purchased the boat / motor, the engine was inconsistent and only sometimes fired up. The main wire to the motor was bad after examining ( it was extremely corroded ) I determined that was the problem. I replaced the wire and still had the same problems. I then looked at the fuel issue ( after reading many post's, I concluded motors need gas, spark, and air ) and found the floats were crack, they were replaced.

I attempted to sell the boat. It took awhile to fire up and then it did. After it fired up initially, it would continually fire up on command. After I let it start and stop about 10 times, it refused to start up again. The SOB wouldn't leave my life.


Still having issues, I stumbled upon the testing procedures and attempted them. They led me to believe either the strator or the control box was bad. I replaced the control box last year and it didn't fix it. Tonight, I replaced the strator and it did not solve the issue.

I am out of options and am ready to "Office Space" this motor with a shotgun at this point. I have no voltage at crank before the distributor. I tested the distributor lead and have nothing.

No shops will work on a motor this old where I am from. Can anyone offer any advice or tips? I would appreciate it.

 

[Faztbullet]

Re: Mercury 650 NO SPARK, im out of options, please help!

Sounds like trigger is bad or mercury switch has it killed...below is link to correct troubleshooting.
Installation and Troubleshooting Guide on www.gobookee.net - free eBook download

 

[FishHunter007]

Re: Mercury 650 NO SPARK, im out of options, please help!

What exactly is the trigger?

and what do you mean by the mercury switch has it killed?

Thank you for the troulbleshooting procedures.

 

[Faztbullet]

Re: Mercury 650 NO SPARK, im out of options, please help!

What exactly is the trigger?

It made into the distributor ...it a electronic set of points basically.

mercury switch has it killed?

This is usually mounted on a 650 on the exhaust cover and it a mercury filled switch that shorts ignition in the event of a impact with underwater object or excessive trim/tilt when running. See link below of picture...
1973 Mercury 65 HP Switch 58124A15 | eBay

 

[FishHunter007]

Re: Mercury 650 NO SPARK, im out of options, please help!

I had previously removed the mercury switch based on a post in another forum. If this switch is not present, would that cause no spark?

What is the trigger located on the motor? I had thought that was the same thing as the strator on the flywheel. I looked through the parts book and could not find anything.

Any help is appreciated, it would be nice to finally get this running!

 

[jbjennings]

Re: Mercury 650 NO SPARK, im out of options, please help!

I will give a shot at your problem. I believe that your motor has a battery CD ignition, with a distributor, right? All your energy from spark comes from the CD box as far as I know. See if you're getting voltage from the cd box by checking the red wire going to the box from your coil. Turn the engine over and check between the red bottom wire on the cd box and the coil. You should get a good voltage reading. Then, if you're getting current from the cd box, see if there's anything coming out of the coil to the main wire going to the distributor. I would also take off every wire on that cd box and clean the contacts and check for cracks or corrosion in the wires. Those wires can rot from the inside out and sometimes if you cut off a little dab of insulation you'll have nothing but a green corroded mess inside the insulation. Any wire on that thing is a suspect for corrosion or high resistance and could be the problem. Are you sure it's a '78? I was thinking the ones that late were 70hp... Anyway, I would start at the powerpack and go from there. The plug wires I'm pretty sure screw into the distributor, so don't booger them up. Be careful with the distributor, because they're hard to replace. BTW, all the stator does is provide current to the rectifier to charge the battery. I'm thinking it doesn't have much to do with spark. Faztbullet is an expert, so I'd listen closely to his posts. I didn't even know my 650 had a trigger. I thought my spark on my 650's were timed by the distributor connected to the flywheel by a belt, and that was what timed the spark. The cd box just supplied the voltage and such to the coil. I'm probably wrong...... I'd bet your motor is NOT a '78, though.
Hope this was helpful, anyway.
JBJ