If the chemical used is not catalyzed, it will, from what I've seen, breakdown over time by the fuel and either turn gummy, or break off in chunks in the tank. Make sure you have a clear filter installed between the tank and pump. And if the fuel looks odd, have it tested. The tank may need 'recleaned' and properly coated. Like anything else, there are quality chemicals vs cheap chemicals that coulda been used in your tank.