Briggs 10hp no spark

I have a 5000 watt generator powered by a 10 hp Briggs and Stratton. I am getting no spark now. When I first bought it, I rebuilt the carb and it cranked up, but immediately quit running. I knew I was getting fuel, so I started diagnosing ignition. I pulled the cowling and I checked the grounding wires. I could get spark with no wires attached to the magneto, so I assumed I had a grounding problem. I traced it to the oil sensor and disconnected it. Fully expecting to get spark, I was amazed when it did not. Before I did all of that, I removed the magneto and tested it with an ohm meter. It showed some resistance, but still no spark when grounding the spark plug. I do not have a spark tester. So I replaced the magneto. Still no spark when connecting and grounding the plug. Any advice would be appreciated. Thanks!