Hello, im new to working on old tractors. My gfs grandfather has ALS and doesnt have long to live so i thought id give him some joy by getting his 58 John Deere 60 running. Hes the original owner and its his baby. Hasnt run in several years. Well i was very excited to get get it running today....it runs well but there is one problem. The fuel in the glass sediment bowl turns black. My hunch is that it has to do with the automatic fuel shut off which is controlled by oil pressure. From what i can gather there are some diaphragms in there that might be deteriorated? Or could it be a carb issue? Am i on the right track? Hoping its not something more serious. Sorry if this is too long winded. Any help would be appreciated!