Mercruiser 120 no spark to plugs

[RMELAN]

I have a 1968 MerCruiser 120. First it would not crank over. There is a shift interrupt switch inside the gear shifter lever assembly I bypassed that at the ignition switch. Now it cranks over. But there is no spark when I pull a plug and ground it and crank it over. I replaced the points, condenser, cap, rotor and coil. Still now spark. Something tells me its some how one of the interrupt switches on in there rear of the engine or on the gear shift linkage or in the gear shifter lever assembly itself. Any ideas?

 

[Scott Danforth]

file your points, then gap them and use a dwell meter to dial them in.

 

[nola mike]

There's a shift interrupt switch on the shift plate at the rear of the engine. Disconnect one of the wires from there. Also disconnect the gray tach wire from the coil (assuming the wiring on your engine is similar to newer models). There's a thread on troubleshooting a points ignition in the "adults only" sticky at the top of the forum. I assume that you properly set the gap/dwell when you replaced the points?

 

[RMELAN]

I set the gap but not the dwell. Would dwell cause no spark?

 

[QBhoy]

Ignition sensor (or distributor sensor as some call it). It runs from here to the ignition switch on some older motors. Might be wrong though. Don’t have any experience on this engine.

 

[RMELAN]

It has spark to the points but not the plug as?

 

[Scott Danforth]

Ignition sensor (or distributor sensor as some call it). It runs from here to the ignition switch on some older motors. Might be wrong though. Don’t have any experience on this engine.

No sensor on points dizzy

 

[nola mike]

It has spark to the points but not the plug as?

Huh?