1970s Mercruiser 888 spark issues

[justinshreve1986]

Hello every one i have a 1970s Mercruiser that i am working on bringing back to life. The problem that i am having is i dont have any spark coming from my coil tower. what i have replaced so far is the Coil tower, spark plugs wires and plugs, points in distributor and gaped at .020, condensor, starter silonoid, battery terminal cables, carborator ignition switch.
does any one have any ideas of what else it could be? i have five wires going to the ignition coil aka coil tower two brown wires on the negitive terminal of coil and the black wire from the condensor from inside the distributor and two white wires going to the positive terminal.
I have tried pulling the plug wire going from the coil to the distributor cap and placing a spark plug testor light connected to the coil tower wire and connecting it to a spark plug at the other end and grounding the spark plug i also connected the spark plug testor light directly to the coil tower its self and grounding it and also tried a multimeter on the positive terminal of the coil if i disconnect the condesor wire from the negitive terminal on the coil i read 12v but if i reconnect it i get lower volts

 

[achris]

Disconnect all the wires on the negative terminal of the coil, then (with the key ON) using a wire from that negative terminal, strike it repeatedly on the engine block/ground. You should get a spark from the coil. If you do, the wiring to the coil and the coil itself are fine. The problem is in the points end of things.

Put JUST the wire from the points back on the negative of the coil (leave the others off, for the moment)... Crank the engine. get a spark? If no, the points need cleaning, or the distributor isn't grounded properly. If yes, reconnect the tacho wire back on the negative of the coil. Test for spark again. If no, replace tacho (or find were the wire is grounded). If yes, reconnect the wire that comes from the shift interrupt switch, test for spark. If yes, all good. If no, then something wrong with the shift interrupt switch or the shift cable.

Chris.........

 

[justinshreve1986]

thank you i will try this tomorrow when i get up and let you know....

 

[justinshreve1986]

i can tell you that i have spark from the negitive terminal and the points are brand new never used and the tachno is also brand new and never used and also has spark comming from it as well the only thing that im not sure about is the shift interuptor but will test tommorow