Hi, any mower mechanics HELP!!! I have an older model briggs 12hp motor it has been going great!! until this morning.When I went to start it the muffler filled up with petrol.I took the muffler off & made sure that all the petrol was gone & checked the carbie & the choke had stuck on.I fixed the problem but it still would not start. I checked the oil only to find that it was really thin & smelt like petrol.Could this be the problem & if so what is the cause & am I able to fix it myself?? Buster2.