The Buick Regal car, which runs 260 thousand km in 2002, produces buzz and buzz noise when the fuel pump works. The cause of the failure: (1) the filter net of the oil pump is too dirty. The fuel system pipeline is loose. (3) injector needle valve card, bad work and so on. Fault diagnosis: because of the fuel pump work, the "buzzing, buzzing" noise, then dismantling the fuel pump, found that the oil pump filter is very dirty, it is suspected that the filter screen is too dirty to cause the "buzzing, buzzing" noise. The failure of the retest car after cleaning is still the same. After the replacement of the new fuel pump assembly, the noise did not improve significantly. At this point, would it be like BMW 528i's resonance due to the resonance of the oil pressure regulator? Next, the oil pressure regulator and tubing were replaced, but the trouble remained. Why are fuel system components changed? Will there be "buzz, buzz" noise from the fuel pump? Later, I learned from my friend that the fault was caused by the resonance of the fuel pump bellows. Troubleshooting: the resonance frequency of bellows can be effectively improved by changing the way of fuel pump return tube and fuel pump wiring harness. Step one: use nylon tape to tie the oil return bellows and wiring harness of the fuel pump and tighten it by hand (bind the middle position of the bellows). Step two: use the slanting tongs to reduce the extra thread ligation. Step three: the fuel pump return pipe is finished and the fuel pump is installed back to the tank after it is confirmed. After dealing with the above methods, the fault is eliminated. Failure analysis: the cause of the above fault is mainly caused by ethanol in fuel. As a result of the use of 10% ethanol (or less than 10%) fuel in many areas, the frequency characteristics of the fuel pump change as a result of the change in the properties of the fuel. The fuel pump of the Regal model uses the latest BOSCH's system. The bottom fuel return injection pump can effectively reduce the working load of the fuel pump and improve the delivery efficiency of the fuel pump. The oil return bellows of the fuel pump are made of blow molding, but they may be softened by oxidation in the long-term immersion of the fuel oil. When the working frequency of the fuel pump is in certain intervals, it may resonate at the softened bellows corner, and even if the gasoline is replaced immediately, it may not be able to stand up. The moment improved the situation. As ethanol penetrates back into the oil bellows, it takes time to release the components.