Rough running, smelly Buick

My daughter has a '91 Buick Regal with the 3.8 liter v-6 and about 56,000 miles. She says that it has been running roughly and she’s smelling a “rotten egg” or sulphur odor. Could this be the catalytic converter has failed? Last year she was smelling gasoline odor and we found that the fuel pressure regulator needed replaced. We also changed the oil at that time as I feared fuel contamination. Could excessive/unburned fuel have entered the exhaust system and “killed the cat”? The car used to sit a lot. When she got it from her grandmother 4 years ago it only had 23,000 miles.



Hope you can help. Thanks.

It could be some bad fuel. Ask her if she fills up at a regular place or anywhere and whether this has been going on through more than one tank or just one.

Sulphur or rotten egg exaust smell is a sympton of a incorrect fuel-air mixture. I would have it looked at.Does your car pass emissions?