1991 Buick Park Avenue

Hi, how long since a tune-up? Are you saying it cranks good but won't start, or it won't even crank? Check for possible trouble codes. If it won't even crank, check starter circuit. If it cranks good but won't start, have a helper crank it while you visually check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure, some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. If you already checked the fuel pressure spec, what was it?