things to check
1. Remove rear seat, check the Lid gaskit holding the fuel guage and fuel pump, it has probably 6 x 10mm screws
2. If it comes during refiling, your rubber pipe from fuel tank to filling port is leaking
3. If tank is pressurizing, check charcoal canister in engine bay.
4. Check O-rings around injectors, Fuel rail ,FPR etc.