No spark now..

Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
So my 1966 merc 950 was running beautifully yesterday afternoon.. After five hours of sitting I tried to start it again and it would not start.. I figured it was due to bad connections so I pulled all my wires cleaned the connections reconnected and tried again... Motor still didn't run so I pulled spark plug to check for spark and have no spark on any of my spark plugs.. Also my plugs are brand new but now look as if they have been in the motor forever.. Any ideas as to what could cause this?
 
S

snayke62

Cadet
Joined
May 2, 2013
Messages
10
Re: No spark now..

I know that theres a wire going to the controls that needs to be connected right and good. i had to rewire my controls. i found a crank/no start condition with dead plugs. once i figured out what wire fed the coils(im assuming)from the controls to the engine harness it fired up. if its intermittant i would assume a bad wire. maybe try tilting the trim in different spots and see if it ever starts sparking. idk. thats my opinion. not worth much tho:)
 
bgc

bgc

Ensign
Joined
Jul 13, 2011
Messages
980
Re: No spark now..

Mercs are infamous for losing the insulation around the wires in the harness. Check every wire for cracks/missing insulation.

The manual has testing procedures for "No spark", I would highly recommend getting a copy.
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

Ty I have a new manual coming in bought it yesterday... I will check all my stuff...
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

So I have many wires that has missing insulation... My father inlaw says my coils are bad because there are dents in them... My brother and I are planning on buying som new wire to replace the broken nasty stuff... All the wires that were not covered by tape or rubber are cracked and nasty... Idk if this is the cause for the motor having no spark yet... My manual has not showed up yet... If anyone has any further advise I could really use it.. I have been working on this motor for 2 1/2 yrs I want to use it this yr lol
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

unfortunately I do not have any more cash to dump into my boat right now.. I am sitting at about 1500 in it and wife says no more until I am back to working a full time job.. :( was hoping it would be a quick fix..
 
bgc

bgc

Ensign
Joined
Jul 13, 2011
Messages
980
Re: No spark now..

Mercs can be expensive motors to work on, I know the pain first hand. A short in the system can BBQ some REALLY expensive parts.....sadly I know this first hand also.......
 
merc850

merc850

Commander
Joined
Jul 7, 2010
Messages
2,050
Re: No spark now..

If you have the non-Thunderbolt ignition (like you said 2 coils) it has 2 sets of points in the distributor
Merc-I-6-wiring.jpgI6-distributor-1.jpgI6-distributor2.jpg these are the important documents for repairing it. Check the voltage at the coil + side; +- 9.5v with switch on, 12+ v while starting.
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

understood.. eventually i want to rebuild this motor and the boat too.. but my brother is a good electrician and I trust him to replace the bad stuff with good.. I am out of college now so I can get me a job once I am working I can purchase more stuff lol.. I am just sad that it might not be up and running this year too.. I need a new distributor cap cause mine has a crack in it. I also need new coils because my father inlaw who is a mechanic said that the dents in them could short them out eventually.. :( I want this thing working this year thanks to everyone on here I had it running then it stopped on me... 1966 merc 950 - YouTube this is my motor running 5 hours before it didnt.. anyway Thank you all that have helped me over the years :)
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

thank you merc850 for that advice and the pics. great stuff.. I will check the coils today...
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

My distributor cap and wires are crap... anyone know where I can get these for cheap? part # 393-1927A 9 this is the problem with my boat having no spark points are wore down and wires so corroded that they broke off when removing the cap.
 
Mortamie

Mortamie

Petty Officer 3rd Class
Joined
Sep 4, 2011
Messages
78
Re: No spark now..

My manual came and I am awaiting a few more pay checks before I can get my new parts.. Once I have purchased the new wiring harness and spark plug wires I will let ya all know if it fixed my problem or not.. Thank you all for the help I have received over the years working on this motor :)
 
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