Normally, fuel pump whining indicates the presence of an underlying problem that may not be neglected. The design of fuel pumps is such that they are supposed to run very quietly; therefore, loud noises signify some malfunctionings relating to flow or pressure issues. A clogged fuel filter, for example, restricts flow, which results in the fuel pump having to fight harder and, therefore, makes the characteristic whine. In fact, flow restriction can cut fuel pressure by up to 20%, straining the pump and, eventually, shortening its life span.
Low fuel levels are another common cause of whining. The closer to empty the tank gets, the more the fuel pump has to suck fuel from the bottom with just that little amount in it, forming air pockets that translate into increased noise. It is statically explained that running any vehicle continuously with a low fuel level can reduce the life of the pump up to 30%, as the pump takes fuel for cooling and lubrication. The problem increases in the case of an older vehicle when the efficiency of the pump has already been deteriorated.
Such whining sounds may also be due to faulty wiring or connections. Poor connections, whether loose or corroded, restrict the flow of power and result in intermittent working of the pump or drawing extra current. In the opinion of mechanics, more than 10% of fuel pumps are related to problems involving electricity, leading to abnormal sounds and, in severe conditions, the total failure of the pump. As one leading mechanic comments, "A proper wiring harness is important for any electric component, but even more critical on high-demand parts such as the fuel pump."
Whining can be worse with heat, especially on longer drives or in hot areas. Higher temperatures make the fuel pump work harder and stress the system since it is not being cooled by the fuel. In fact, studies indicate that extreme heat can shave as much as almost 15% off fuel pump efficiency, which could be an important factor in very hot regions or during peak summer months.
Besides, some of the fuel pumps available in the aftermarket, especially the high-performance-rated ones, will be noisier because of the higher flow rate and pressures. Those who install performance pumps in their vehicles have to live with the increased whining as a trade-off for higher output these models give. For anyone eager to know more about fuel pump operation and selection, refer to Fuel Pump.
Whining noises, if left unattended early, may lead to serious problems such as a complete failure of the fuel pump or engine misfires. The regular maintenance of replacing filters and keeping a full tank will keep the fuel pump in optimum condition and avoid drops in performance and expensive repairs.