mercruiser 120 stalling

[captainnate]

1972 starcraft nova

sn 3331071

Thanks for reading, and thanks for any help. My old 1972 mercruiser 120, sn# 3331071 is stalling half way through the day. The last time I took it to the lake it ran fine for half the day (with intermittent use). When I started heading back to the dock it stalled after a minute or two. After 10-15 minutes it started for a minute or two and then quit again. I repeated this for the next two hours. With the help of a 40lb trolling motor I finally made it back to the launch. I took the boat to the mechanic, but they are super busy, so I either have to do it myself or wait a month for the mechanic. The mechanic did say it is most likely the coil, or the purple resistor wire. So a couple questions.

If I upgrade to an electronic ignition, will that solve my problems? Is there a way I can avoid that resistor wire with an electroinic ignition? Otherwise, how do | test the coil and that purple resistor wire?

Also, since this happened at the lake (about 2 weeks ago) I ran the motor for 45 minutes while it was on the trailer at a boat ramp. It ran fine, and never quit on me.

thanks again,

Nathan

 

[boozer1966]

I have experienced a similar problem with an MCM 140 from 1984. I switched to Pertronix electronic ignition and it made a huge difference.

 

[jaa241]

Make sure it's the pertronix II !

 

[captainnate]

Update. I put in the Pertronix ignitor 2 and a flamethrower 2 coil. I cut out the resistor wire, as the instructions say. I adjusted the timing. It seems to be running well in my driveway on muffs. Hopefully overheated coils and or resistor wires are behind me.