The fuel pump typically has electrical-related problems concerning relays, corroded wiring, or weak ground connections. This can interrupt the power supply to the fuel pump and cause a range of engine performance problems as a result of uneven delivery or lack of fuel.
One of the most common culprits for fuel system electrical issues is a bad fuel pump relay. The relay modulates the passage of electrical current to the fuel pump, so that a failure can prevent power from reaching it (sporadically), and cause an engine harder to start, walking or until completely shuts down. A failing relay may decrease your fuel delivery by 20% to 30%, since the pump can no longer maintain the correct pressure which, at idle speed is around 40-60 psi. When cars are diagnosed with automotive diagnostics, it is rare not to see almost 10-15% of fuel pump failures caused by faulty relays.
One of the most common issues is corroded wiring; especially in older cars or those constantly exposed to severe environment. The insulation on electrical wires can be degraded by moisture and contaminants over time, leading to poor conductivity and potentially short circuits. The short circuit will either cause the pump to not get power at all or it will make the pump run in a funny way. Wiring corrosion can result in voltage drops of 1-2 volts, which may not seem like much, but very few fuel pumps will function properly on anything less than about a steady 12 volt supply. Problems like this are common in areas with high humidity or vehicles are regularly exposed to water / road salts.
The ground connection is also a common problem in fuel pump electrical issues. No correct ground for these causes the electrical circuit is not complete thus preventing the pump from functioning. Intermittent power to the pump from a loose or corroded ground causes erratic fuel pressure and crapy engine performance. An open ground is typically diagnosed by testing the resistance of this wire back to the vehicle chassis with a multimeter. Above a few ohms of resistance could suggest grounding issues and it could affect fuel economy by as much as 15-20%, from the erratic flow of fuel.
Thousands of vehicles were recalled over fuel pump relay issues in 2018 by General Motors. These relay failures caused the fuel pumps to shut off suddenly, which in turn resulted in stalling and created a litany of safety issues. The massive recall demonstrated the importance of electronic controls to fuel system reliability.
Like the car visionary on Enzo Ferrari claimed, "The Engine is red an auto beating heart but the Fuel pump keeps this Moving soul alive. The heart of the car, the fuel pump would not be able to perform correctly without electrical components supplying and providing it with power.
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