The most substantial cause of cng or lpg injecotr failure is by far from deposits. Field experience proves that lp has the highest deposit forming tendency bar none. I can back that up with photos, data, field experience and user experience. There is much talk of fuel quality re lpg as motorfuel but the talking heads put more energy into their golf game and not the fuel. LPG is not inherently bad fuel but just like gasoline, even if it is of high quality there needs to be some additive present that cleans up deposits that are inevitably going to form and to keep injectors and valves clean.. Even if the fuel is not the direct cause it has a role with interaction.. oil gumming up parts is a real issue. Untreated or even poorly treated lp leaves heavy residue that precision parts with a few microns of clearance just cannot deal with. For precision fuel delivery the durable technology exists but finding dependable sources of motor grade lp is like a needle in a hay stack.
And to answer your question, motor grade lp sure is odorized but organic sulphur levels are way too high most of the time by orders of magnitude. Many times our own testing revealed +500ppm.. +100 is the lowest if the odorant is low. Needs to drop under 20ppm for catalyst and o2 sensor life aside from injector life. Sulphur deposits are very problematic and tough to remove from injector internals even with good chemicals that are safe for non metalic components.
I am not sure but a few trials of additives are supposedly underway at clean fuel usa and elsewhere here in the usa and ENI agip may also have a trial in your home country but I cannot verify the efficacy of their products real world deposit control.
Ciao, James "Turbo" Cohen
The injectors in such a system would be similar to typical petrol injectors (ie not a venturi carby system)