The Minnesota Center for Automotive Research at Minnesota State University, Mankato, recently published the results of its test of fuel pumps and sending units using gasoline containing 20% ethanol. The results show promise for gaining EPA approval for 15% ethanol blends (E15), which the ethanol industry is currently seeking.
The study compared running fuel pumps and sending units for a period of 4,000 hours (more than 166 days) in gasoline, E10 and E20. The researchers (Gary Mead, Bruce Jones, Paul Steevens, Nathan Hanson and Joe Harrenstein) studied eight models of fuel pumps. Three of each type, one for each test fuel, were used for a total of 24 pumps. To see which fuel pumps were tested and test results, visit www.mda.state.mn.us/news/publications/renewable/ethanol/e20endurance.pdf.
In addition, the researchers studied three different manufacturers’ fuel level sending units. One of each of these three types was tested in each of the three test fuels for a total of nine sending units.
The researchers reported that ethanol had a cleansing effect on pumps, sending units and test fixtures. When immersed in gasoline, however, these items were coated with a grayish-black residue. Some pumps tested in E20 had light surface corrosion, but not to the extent to affect their function, the researchers said.
The researchers found no clear differences in pump performance between any of the fuels tested. However, the commutators of several of the pumps tested in gasoline wore substantially more than in either ethanol fuel blend. This wear was significant enough that if the test would have continued longer, several of the pumps tested in gasoline would have stopped because their commutator would have worn through. The researchers concluded that, overall, E20 did not cause any greater negative effects than gasoline or E10 on the fuel pumps tested.
The researchers also found no significant differences in performance or in failure between the sending units in any of the three fuels.