A gas turbine engine system includes a compressor, gas turbine, and combustor including a plurality of late lean fuel injectors supplied with secondary fuel to its interior. The gas turbine engine system includes a wash system in communication with the late lean fuel injectors. The wash system includes a water source; water pump; anti-corrosion agent fluid source with an anti-corrosion agent including a polyamine corrosion inhibitor; anti-corrosion agent supply piping in fluid communication with the anti-corrosion agent fluid source; mixing chamber receiving water and anti-corrosion agent to produce an anti-corrosion mixture in fluid communication with the mixing chamber and the plurality of late lean fuel injectors. Fluid from the mixing chamber including the water, the anti-corrosion agent fluid source, or a mixture thereof is injected, while the gas turbine engine is off-line, into the combustor at at least one of the plurality of late lean fuel injectors.