Were is it on the 355, is it in the pump or is it in the fuel line? Please
The fuel non-return valve is screwed into the end of the fuel pump and is not sold seperately by Ferrari, however you shouldn't have any problem buying the valve on it's own from any Bosch agent. If you have the twin pump (M2.7) it's worth changing both valves. MW
Just spotted, completely by accident that 348's have a similar pump and the valve, which looks the same is sold as a spare part. The Ferrari part number is 95991104 (£102.10) - no doubt it would be cheaper directly from Bosch, but if you are stuck it's a lot cheaper than a fuel pump. MW