Detergent was accidentally put into the gas tank and the motor did run until obviously the detergent made it's way in. I had flushed the gas tank and the carburetor and got it to run. After leaving idle for 3-4 months it will not start. I did change the plug. Also I checked that it is getting spark.
I'm wondering if any detergent residue may have damaged gaskets, etc.
Any ideas on how to fix this? Would I have to rebuild the carb for example?
First thing check that you have a good flow to the carburetor. Unless the carburetor has damage not a rebuild but I would start with a carburetor cleaning. If the detergent did damage to the internal parts of the carburetor you may have to replace it? Just remember you need spark, fuel, compression, and timing for the engine to run.
I gave cleaning a try with some carb cleaner. I thought I was successful at first when it started up. But then it died again. I think it probably was just running on the carb cleaner. I think I will go the new carb route.