Mercruiser 120 won't start!!

[Ryan's Rally]

I need some serious help, because I have replaced a bunch of parts and still cannot get my boat to start. I have a 1978 mercruiser 120 motor. I was not getting fuel or spark when I tried to get it running this year. I installed a new fuel pump and am now getting fuel at the carb. I also installed new spark plugs (MR43T gapped at .035), new spark plug wires, new distributor cap and rotor, and I ?upgraded? to the Pertonix electronic ignition kit (1146a) and flame thrower coil (40511). I have dual batteries that are both fully charged, and I have also replaced the starter. I have triple checked to make sure that the spark plug wires are in the correct firing order. Cylinder compression is good 140, 125, 130, 125. I am now getting a weak spark. When I hook up my spark tester, I am getting a thin orange spark on 1, 2, and 3, but a thicker orange spark on #4. What am I missing?

 

[Ryan's Rally]

And also I have a Mercruiser service manual #3, but the troubleshooting for not starting is somewhat vague. There is no moisture on ignition components, battery connections are clean and connections on starter are clean, and I believe that plugs, wires, dist cap, rotor, and coil are ok since they are new. Condenser and points are ruled out since i have changed to electronic ignition. This leaves ignition switch, shift interrupter switch, shorted tachometer, ignition timing, or faulty ignition resistor wire, but I'm not sure how to diagnose further. I called a few places near me and nobody is willing to work on it bc it's too old . Any help is greatly appreciated.

 

[thumpar]

Did you run a full 12v wire to the pertronix?

 

[Ryan's Rally]

Yes, first I connected it to the (+) on the coil, and then I tried connecting it right to the battery. Still won't start...

 

[Fishermark]

Run 12 v directly to the positive side and disconnect everything on the negative side of the coil except the pertornix and see what you get.

 

[Fishermark]

Plus, have you checked the timing?

 

[Ryan's Rally]

Thanks guys, but I got it figured out. The rotor ended up being stripped (the plastic part that keeps it in place). It would still spin when I had the dist. cap off, but was not seated correctly which was causing spark issues. Took me a while to figure it out, but once I took it off of the distributor and saw it, I got a replacement rotor and it fired up immediately.