1971 merc 80 thunderbolt ignition system testing procedure- no spark

wildlifeon1

Recruit
Joined
Apr 20, 2003
Messages
2
Does anyone have a procedure that can be used on the driveway to test the ignition system on a 80 hp merc with the 'brown' coil and the molded in coil pickup in the distributor? the engine has been extensively rewired, spins over good but does not produce a spark. The coil has been removed and ohmed out to compare with a known good coil and checks out ok. The pickup due to the condition of the old wiring was rewired carefully and at the time ohmed out sucessfully. <br />All electrical connections are good and tight. there are no wiring problems apparent.It looks like a module problem, but i have found no info on test procedures other than have it checked at a boat shop. (prefer not to go there thanks) I have a spare distributor but don't trust the wiring on that one either as its original and fragile. However it ohmed at 830ohms (X200 scale) and the original ohmed at 930 ohms across the black and brown wires. checking across the black white or the brown and white wires showed open on both distributors. I am used to dealing with electronics as its part of my job. So, anyone got any ideas as to how i can check the 'brain box' :confused: :confused: ??
 

ledgefinder

Ensign
Joined
May 2, 2002
Messages
916
Re: 1971 merc 80 thunderbolt ignition system testing procedure- no spark

We'll need your serial number to go further, or at least tell us the number of connections to your CD box - should be 4 or 7. Chances are you've got 4, which means you have a somewhat oddball ignition that Merc just put on the 800 between 1971 & 72. If you've got 7, smile - that system is one of the most common they made.<br /><br />Can't diagnose until we know which one you have. In the meantime, wiring diagrams (with the serial number breakout for the different systems) is here:<br /><br /> http://www.maxrules.com/oldmercs/Wiring/1966ona/30.PDF <br /><br />The parts for the oddball aren't as hard to find as I'm making out, Merc sold a lot of these motors & used parts are fairly commmon.
 

mellowyellow

Vice Admiral
Joined
Jun 8, 2002
Messages
5,327
Re: 1971 merc 80 thunderbolt ignition system testing procedure- no spark

believe that year had 2??? :confused: <br />switch 'em and see if problem follows box...<br />fire up at night and look for arc's.<br />get a manual (bottom left) or local library.<br />good luck,<br />M.Y.
 

wildlifeon1

Recruit
Joined
Apr 20, 2003
Messages
2
Re: 1971 merc 80 thunderbolt ignition system testing procedure- no spark

I TRIED THE SWITCH AND THE BOX CHECKED OUT OK.The problem was in the distributor pickup coils. it runs great with a new distributor. thanks to all who replied
 
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