They connect fuel pumps to the power they require in order for them to run properly and consistently. It needs proper grounding due to any irregularities in the power supply that may hamper with its performance. The fuel pump generally uses a ground wire that is hooked up to the vehicle's frame or one of its designated grounding points on the body---unless this specification was relocation friendly. This connection helps ensure that the 12-14 volts of power from the vehicle's battery and alternator flow nicely to pump, ensuring a reliable stream of electricity for successful fuel delivery. Poor grounding can even cause a voltage drop of just 0.5 volts reduce pump efficiency by over ten percent which affects fuel flow and engine performance,
In most cases, automakers suggest that dealers inspect ground connections between 30k and60-miles, or as part of regular maintenance; if power isn't grounded properly it can really eat into the current. There are different factors that cause this, for instance corroded terminals create resistance which make the fuel pump work harder and might overheat it or bring some noise. On high-performance applications where fuel pumps run at higher pressures, like 60 PSI or more (where inadequate grounding not only results in less efficiency but also may decrease the life of your pump by as much as over 20 percent).
Those are likely in areas that get moist, salt or dirt everyday and a clean sturdy connection is very important. Corrosion is a major issue when the contaminants enter into pumps, which further affects grounding of the pump. That could sound like it's running erratically and not flowing well, much in the same way a fuel system problem might. In the ground circuit, many technicians use a multimeter to measure resistance (should be nearly zero ohms) between points in metallic contact.
Top-tier fuel pumps which have been manufactured by companies such as Bosch normally present reinforced ground connections and operate properly in hard warehousing environment. But maintenance checks are going to be the key at preventing those moments of panic. As you know, it is always wise to save money but as the saying goes “The bitterness of poor quality remains long after the sweetness stingy shopping has been forgotten” this serves a good reminder that buying quality parts and maintenance should not be cut in order to save an extra dollar especially in fuel pump. Keeping the Fuel Pump on a firm anchor enhances overall efficiency, decreases noise levels and extends its functional life cycle which in turn helps maintain vehicle reliability.