I think I have read about all the forums on this subject, and pretty much checked them all off, and I am still stuck. My problem is a no spark issue. I have a spark checker that I have used on small engines for years, if the spark will jump the gap, it will fire under compression. With the plug out, I have good spark, plug in, no spark. These are some of the things I have done with basically no change in the problem. I had bought a new battery when I got the scoot before I knew about this problem. Once I got into it, and reading all the blogs about batteries, I bought another one with the CCA of 175, the same as what came with it. I fought with the theory of possibly starving the ECU while cranking with the plug in. Voltmeter proved that wrong, but still I used another battery to power everything but the starter, no change. Okay, so it is not voltage drop, it does crank slower with the plug installed, so could it be the signal from the pickup/pulsar/crank position sensor. It ohmed out correctly and I really hated to do it, but pulled off the crankcase end to get to it. It was melted pretty badly. Oh boy, thought I had it, replaced the coil , checked the gap, running about .015, perfect, buttoned her back up, no change. I have ohmed out the ECU and connector to the manual, everything checks, removed and replaced all ground wires and have used dielectric grease on everything. Checking the output from the pulsar coil, it is showing about .45 volts AC cranking without the plug installed and maybe .42 with it in, not enough to make a difference one would think. I am showing over 12 volts going to the hot side of the coil as well as the power to the ECU while cranking. The only code she is throwing right now, is the O2 sensor because the exhaust is still off from changing the pulsar. I keep thinking it is something stupid and when I find it, she will purr like a kitten, because I have about left no stone unturned, including valves. I have checked continuity from the ECU to the signal side of the coil along with about every wire in the harness. I am starting to look real hard at the ECU but everything says it is okay, it performs the precheck perfectly, throws a code when it should, but what else is there. I have cranked it long enough on a couple occasion that it has started, once running, it runs perfect. You can tell when she is going to start as the tach starts to jump. Any and all suggestions will be truly appreciated.