Repair station Technician reported issues with UL94 aviation fuel dissolving cadmium and holding it in suspension; causing clogging of fuel system components. Technician stated pilots are reporting loss of engine power.

Narrative

Increased frequency of maintenance required on carburetors and fuel injector systems due to suspected cadmium particulate matter being found in float bowls; fuel injector nozzles; fuel screens and fuel jets. This impacts fuel flow and metering; impacting engine performance due to restriction of fuel flow. This phenomenon was observed on aircraft during unscheduled maintenance due to complaints of loss of power and also during routine scheduled maintenance. Particulate accumulation also found in check valves; auxiliary fuel pumps and mechanical engine pumps. Clumps and screen obstruction observed. This has been observed over the past four months; since aircraft started using UL94 (Unleaded 94 Octane). The exact source of the cadmium is not definitively determined at this time.We suspect the cadmium is held in suspension in the fuel and in addition to accumulating and clogging the fuel system some particles are entering the combustion chamber with unknown impacts on cylinders; valves and exhaust systems. A simple experiment was conducted. Aviation cadmium bolts were placed in 100LL and UL94 for a few hours. The bolts in 100LL remain intact with no change. The bolts in UL94 showed flaking with particles suspended in the fuel sparkling. Cleaning of all fuel parts in the fuel systems clears the problem but it reappears. We are concerned since we have limited experience with UL94 and have not seen anything like this in our careers that total over 50 years together as A&P and IA.