Mercury 650 Rotted Trigger Wiring

[joepcdr]

Per a previous post that I placed. My 650 seems to be from around 1974. I've been visually inspecting the engine for a couple of days now to get a handle on what needs immediate repair externally. To my disappointment I've discovered that the wiring to the trigger is rotted all the way up to where it enters the distributor. I haven't pulled it completely apart yet to see if there is anything left to splice to. I'm not counting on there being anything left personally. With that being said, I'm going to squirt a bit of oil in each cylinder and work it through before I do a compression test. If the compression test turns out to be ok on all three cylinders is there anything I can do to bypass just to see if she'll run.

I've tried looking at the parts breakdown for the distributor on iboats and couldn't find the trigger in the parts break down. So I'll need to have the correct part number I'll need to attempt to acquire to get this little beast running. With that being said as well is there a possible upgrade I can get that would work as the trigger replacement.

Thanks in advance!

 

[Scott Danforth]

you need the trigger to fire the ignition.

you can replace the trigger

look at the merc manuals to get the part number

 

[joepcdr]

Scott I did some further digging last night after I made this post. From what I can tell, somebody please correct me if I'm wrong. But it doesn't look like the trigger is available to purchase for this model anymore. This is the type that's built into the upper distributor housing. I found some new old stock running upwards of $400 plus. For that price I'll scrap the motor and sell it for parts.

 

[racerone]

Good decision.----An early to mid 1980's Johnson / Evinrude 70 hp is a far better choice for a motor.

 

[joepcdr]

The problem we've got here in Kansas where I'm from is your dealing with three types of types of people in terms of boat parts. Those who know their crap doesn't work and they want to pawn it off, those who have the parts, but because they are the only dealer in your area they mark up the price 150%, and those who think their 30 year old motor is still worth $2000. It's really hard to find anything of decent vintage that runs and you can get parts for in my region. There aren't to many guys that work on boat motors in my area at least.

 

[sutor623]

Joe give me a serial number. I have a good used trigger left over from my 650 from a few years back.

If the motor is a '74 it should be a 3 cylinder.

 

[sutor623]

Is this the trigger for your motor?
http://www.ebay.com/itm/Mercury-650...ash=item25d1902ff1:g:xDsAAOSwKOJYGKJv&vxp=mtr

 

[joepcdr]

sutor623 the serial number that I have for the motor is 4051304. The one that is listed on ebay looks very similar to what I need. I really need to finish pulling it apart to verify. But it sure looks close.

 

[ajgraz]

Too bad CDI electronics doesn't make what you need. If it was a 1975/1976 or later Merc 3cyl...

Be very careful buying used--or even "New Old Stock"--ignition parts for your 1970's Merc. They frequently come with pre-rotted wiring just from sitting on the shelf. Back then the manufacturer used inferior insulation compounds that were highly acidic, and the wiring simply self-destructs over time.

The 70's may have been great for music, sex and drugs, but not so good for marine and automotive technology.

I'm with racerone, if it was me I'd get out of that motor and into one you can get reliable parts for.

 

[joepcdr]

Since I know the wiring is shot. I'm going to try something totally insane this evening. Because in all honestly I can't make it any worse! I'm going to try to heat up that compound they used to seal it into that housing and see if I can get lucky enough to find something that I can afix new wiring to. If anything it would at least give me a better understanding how the trigger actually works. Because in my mind I'm picturing something like a switch that's being pressed by a lobe as the shaft turns.

 

[merc850]

Be careful of the metal tab that is over the copper disk don't try to lift it up if you break it off the unit is done - there is a terminal block under the epoxy and I managed to get to 2 terminals on mine; here's how it works:

 

[joepcdr]

Well I took a look at the what CDI had to offer for the new models of the 650. The trigger for the 75 looks practically identical to what I have except for what appears to be a extra ground wire. So I emailed CDI for giggles to see what they say. On a more interesting note and I wished I booked marked the site. But I was looking at another forum there's a gentleman facing a similar issue to mine on a 1970's 650. Somebody made the comment that the ignition system off of newer years should be compatible. They didn't make any indication as to what might need changed out or modified. But this might be something worth investigating unless someone knows different.

 

[joepcdr]

Be careful of the metal tab that is over the copper disk don't try to lift it up if you break it off the unit is done - there is a terminal block under the epoxy and I managed to get to 2 terminals on mine; here's how it works:

Do you recall if you had to heat yours or use a dremel to get it to it. Either way I've got access to both? Thanks for the article. Basically it reads to me like that trigger is a glorified magnetic reed switch.

 

[merc850]

This procedure has been covered in this thread http://forums.iboats.com/forum/engi...spark-at-coil-but-not-at-plugs-wires-check-ok
No it has no moving parts uses magnetic fields; you have to take the rotor and disk out of the housing first (which can be tricky) then you can clean out the compound - I used a Dremel with a ball fitting.

I bought the CDI unit 6 yrs.ago and it was worth it it - even comes with new bearings (important!). I would buy a new unit and then work on the old one following the instructions that come with the CDI one.

 

[joepcdr]

I bought the CDI unit 6 yrs.ago and it was worth it it - even comes with new bearings (important!). I would buy a new unit and then work on the old one following the instructions that come with the CDI one.

CDI cuts off at 75 model year. From what I can tell mine is a 74. Looking over the parts diagrams I can't tell what's really different between 74-76 myself.

 

[merc850]

In 1976 they went to distributor-less ignition but from 1972 to 75 they used the distributor.

 

[joepcdr]

In 1976 they went to distributor-less ignition but from 1972 to 75 they used the distributor.

So in theory then the 75 trigger should work without an issue on my 74? If that's the case I've got sort of a game plan! This is a motor I don't know the history of and I'm finding out that the boat it came with has some stringer rot issues. The more I dig into things the more of a lemon I think I got. I'm not crunched for time so I'm not in a hurry. But my plan is before I spend any money on the boat itself is to get the motor running with as little money possible. Knowing at some point things that I jury rigged will need to have a permanent solution put in.

I already know that it's going to cost me few hundred to repair the stringers, refoam and fiberglass a new deck. The only good thing I can possibly say about this boat is that it has a good trailer, doesn't have holes through the fiberglass and water doesn't appear to have penetrated the transom.

 

[merc850]

Ask CDI if that's who you're going to (I'm saying yes); you should also check the thermostat in the block, the Lower unit oil and fuel pump assembly.

 

[joepcdr]

Ask CDI if that's who you're going to (I'm saying yes); you should also check the thermostat in the block, the Lower unit oil and fuel pump assembly.

I had to give my 63 Johnson a run through when I got it. The only issues I have with it is the shift lock mech seems to stick every now and again and the gouge in the crank from years of shearing the flywheel pin.I fired it up after sitting for two years a couple weeks ago and let it burn through a 1/4 tank of fuel while sitting in a trashcan full of water. She sounded as hungry as ever!

 

[joepcdr]

You guys will love this. Curiosity got to me and I got tired of waiting for CDI to email me. So I called them! Basically I'm not able to get the part new from them. But, they are more than happy for me to send them my part to be refurbished all for the price of $432.59.