Katie, there is only 1 petrol station located within the suburb of Richmond;
Liberty Petrol Station located at 195 Richmond Road, Richmond SA 5033 / (08) 8443 9120. You can get to it from either Brooker Tce or Richmond Rd.
However 2 other petrol stations close by include;
Woolworths/Caltex located at 409-415 South Road Keswick SA 5035 / (08) 8293 5495. You can get to it if your travelling South on South Rd or West out of the city on Richmond Rd. Also another Woolworths Petrol Station is located at 130-132 Marion Road, West Richmond / (08) 8352 6289, you would be able to get to this if your travelling on the beach side of Marion Rd or off of Trennery St.