A fuel pump relay should make a clicking sound when you turn the key on, as it's receiving power, but might not be working properly. This is what controls the power going to the fuel pump, and that the pump gets enough electrical current to function properly. Relay cycling (clicking over and over again)The clicking sound could be the relay cycling on and off, which can mean a variety of potential problems.
A bad relay itself is a very common cause of the clicking. Relays wear out mechanically with habit and exposure to heat. A relay can begin to fail after 100,000 miles and may begin losing the connection intermittently. Thus it clicks in and out of the electrical circuit, causing an intermittent clicking noise.
A faulty fuel pump could also be the problem. A pump that is drawing too much current because of internal damage or blockage can also trip the relay. A fuel pump will ordinarily run at 12 volts, but the relay will make a clicking sound if the current load on it is over specified rating; this is to prevent overheating or shorting in electrical system.
Broken wiring: along with the corrosion or loose connections, bad wiring may cause relays to start clicking. Faulty wiring can cause the relay to operate intermittently as a result of non consistent operation, and thus erratic power delivery. One vehicle owner told us the relay’s clicking sounds went away after he tightened the ground wires, suggesting even small problems can generate large grumblings.
The fuel pump relay clicking in these cases could be due to a low battery or alternator going bad. As soon as the battery voltage drops off by 12 volts, the relay might flicker on and off trying to compensate for the less power – this is definitely something which may also be heard as a loud clicking noise. Testing to ensure battery and alternator output power is available can rule out the electrical system as well.
Ford: In 2020 a recall was issued by Ford for more than 50,000 vehicles with fuel pump relays that clicked because of bad components. The fact even the manufacturers required a few goes to get relay reliability right— especially in demands of high-throughput systems like the fuel pump — shows how hard it can be.
When your fuel pump relay develops an issue clicking wise, it is important to test both the actual relay, as well as check the condition of corresponding wiring and fuel pump before anything else gets expensive. Replacing a Fuel Pump or relay that is worn-out can often bring the car back to operation and stop clicking.