MY 2007 accent has a hard time starting only when I put gas in

Your Accent has an Evaporative Emissions System which incorporates a valve, called the purge control solenoid valve (PCSV). If/when it sticks open, it will continually/continuously apply a vacuum to the charcoal canister, creating a 'RICH' mixture condition after re-fueling. The charcoal canister absorbs fuel vapors during refueling. The PCSV operates to vaccum/**** those absorbed vapors from the charcoal canister to the engine intake to burn them. This is most likely the cause of what you describe. Go to www.hmaservice.com and register your vehicle by VIN #..
you'll then have access to wiring diagrams, shop manuals,
service bulletins, illustrations, etc.