Mercury 4.5 Iron Seahorse Spark Issue

[dobrosailor]

Went out on a limb and spent $90 on a 1977 Mercury 4.5 long shaft for my Catalina 22 from the original owner. He only used it on Sundays couple times a year ;o) but it really appears to have very low hours and to have been very well maintained. Last memorial day he was fishing and "it stopped" and never started again. His mechanic sold him a new electronic module (potted orange module with two posts and three screws) for $134 which he tried to install then gave up and put the whole thing on Craigslist.

I found a clean motor with good compression but very crusty wires so I rewired the crusty ones and installed the new module, luckily he took photos before he disassembled the motor so I "think" I have it wired correctly but my old shool vintage car years found connecting the condensor to the positive terminal of the coil a little disconcerting, usually they connect to the points on the neg side but I cannot find a wiring diagram on the internet and I have no experience with systems lacking a battery. Still no spark (shut off button disconnected from coil). I came across this post from 2003.

http://forums.iboats.com/forum/engi...s/481843-4-5-mercury-still-spark-intermittant

which has some great data sheets on testing stators, coils, condensor and the electronic module but it is not clear just how to execute the tests, in place or disconnected? For instance, it shows the coil with a ground which I do not see on my two post system, one post goes to the points which are funky but seem to work fine in an ohm test, dressed them up a bit. I am very comfortable with a Volt Ohm meter, any guidance on how to test each module to work to the offending culprit would be very appreciated.

 

[merc850]

Here's the wiring diagram, I think that the capacitor is charged/discharged to energize the coil.
Check the back of the coil for a ground wire.

 

[dobrosailor]

Thanks for the wiring diagram, very helpful - I was wired correctly.

Well I was looking around and found the CDI website which is a wealth of information. Turns out they are in Huntsville right on the other side of the fence at the Huntsville airport, which I happened to be going to attend a conference last week. So I took my entire spark system off the motor, from the plate that turns to advance the timing to the spark plug and put it in my suitcase. I landed and went to the CDI headquarters, a nice building with an impressive lobby. I fully expected to be laughed out of the building when what one of my friends called a "Magic Redneck" came around the corner looking like he was ready to launch his sparkly bass boat at 4:30 am. He did a "laying of hands" using a multi-meter and knife that I swear had everything including an engine hoist in it, and sent me home with a - gulp; $70 condensor and wow do I have spark! In all my years of hot rods, high speed motorcycles and boats I have never seen a spark like these old mercs! He told me it will clear a half inch and to be very careful because, "That will light you up!".

While it was hard to cough up $70 for a condensor, I was happy to only spend $70 to get spark. I highly recommend doing business with these guys, they have experts and quickly get to the point(s) so-to-speak...