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The growing use of tribotest has been helping the researches to understand the actuation mechanisms of additives on the friction and wear control of engine parts. But, it is common to observe differences between the tribofilms formed in real situation from that obtained using tribotests. Furthermore, the automakers have difficulty to correlate the results obtained using tribotests with that performed using engines in dynamometers. For the piston ring/cylinder bore tribosystem is almost impossible to reproduce its real tribosystem using tribotests. Therefore simplifications are necessary and they affect the tribochemical behavior of the tribosystem. To understand how these simplifications and the test parameters affect the tribochemical behavior of the simplified tribosystem is critical to design a tribotest that correlate well with the real situation.

Two electrical fuel pumps were performed with different fuels in two different vehicles. The pumps accumulated 60.000 km and 190.000 km in passenger cars. Both vehicles and pumps were designed to operate exclusively with gasohol (E22), one of the pumps was tested with 60% ethanol in volume of gasoline blend (E60) for 60.000 km from June-2001 to February-2004. The other pump was tested with gasohol (E22) for 190.000 km from August 2000 to February-2004. The test conditions represented the actual use of the vehicles. Such test is not common vehicle manufacturers practice application because it requires a considered long period of time for evaluation procedure. This test helps both the analysis of soak time influence and the running time. This paper presents a tribological analysis of the components in order to compare the influence of both fuels on wear mechanisms or other degradation that could be influenced by the non usual E60 fuel.