Pertronix ignition on a Merc 3.7

[Ugarph1982]

I have asked this question on these forums before in a roundabout way, but I have a little bit more information now. I am experiencing some intermittent hesitation at higher rpm’s on my MerCruiser 3.7. When the issue occurs, the tachometer begins to jump around a bit. I have unplugged the tachometer at the coil to see if the tach was causing the problem. It did not correct the issue. I have the Pertronix 1146A pick up and the flamethrower coil 40611 3ohm, which is the enamel coil. I just replaced all of the main hot and ground leads on the boat and have a solid 12 V at the coil with the engine not running.

I have purchased a new coil 40511, which is oil filled, to see if the coil itself is causing the problem. I also have a spare pick up that I will install in the distributor to rule that out. Before I tackle these problems, I wanted to get anyone to take on whether or not the carb could be leaning out at higher rpm’s. I assume not, because the tachometer jumps around when the stumbling occurs. I believe this is an electrical issue.

When the tachometer is jumping around and the stumbling occurs, none of the other electrical equipment on the boat acts erratically. This only manifests itself in the ignition.

any insight from the wealth of knowledge on the side would be greatly appreciated. Thank you.

 

[kenny nunez]

It may be the shift interrupter switch . If the shift adjustment is too far in forward that could be the problem. Disconnect the throttle at the carburetor, start the engine, shift to forward and push the throttle all the way, then go look at the interrupter switch lever roller to see if it is still centered in the “V” notch. You may have to adjust the shift cable anchor to reduce the stroke.

 

[stonyloam]

Check your distributor ground.