Causes of Fuel Pump Failure and Signs to Identify a Failing Fuel Pump

Fuel pump is one of the most important components in a vehicle’s fuel delivery system. If it is doing well, fuel delivery system functions normally. But, once the fuel pump fails, the car engine ceases to run. However, the failure of fuel pump and the inconvenience it causes can be prevented by identifying the early warning signs.
In this article, we will discuss the common causes of fuel pump failure and its warning signs.

Causes of fuel pump failure: There are more than a couple of causes which can make a fuel pump fail. They are as follows:

Broken wiring: Broken or faulty wiring in the vehicle’s fuel system prevents the current flow to the fuel pump from the relay. Even the corroded, loose, melted or burnt wires/connectors, and poor electrical grounding can restrict the current or voltage flow from the fuel pump relay to the fuel pump, thus, affecting its functioning Рpumping fuel to the engine.

Problems in the fuel tank: Presence of dust/debris, rust or dirty fuel in fuel tank can result in the malfunctioning of the fuel pump. During cool and humid weather, when the tank is low, fuel tank gets moist leading to the oxidation of fuel tank and formation of rust. As the fuel pump is located inside the fuel tank, the rust will be ingested in to the fuel pump, bringing about its failure.

Clogged fuel filter: Usage of dirty fuel or presence of contaminants in the fuel tank can clog the pickup strainer or filters present in the fuel lines. This results in low pressure and low peak flow of fuel that weaken the functioning of fuel pump.

Clogged filters are generally associated with damaged fuel line connectors/splits or cracked hoses or kinked fuel lines that lead to leakage of fuel. These cracks or leaks on the fuel lines can create vacuum leaks, which disturb the air-fuel ratio, thus, making the engine run lean.

Driving with low fuel level: The durability of the fuel pump depends on the lubrication and the cooling provided by the fuel. Running your vehicle on a low gas tank frequently, may heat up the fuel tank much quicker, ultimately overheatsing the fuel pump. As a result, due to the lack of lubrication, the fuel pump becomes dry and gets damaged.

Identifying a bad fuel pump: Failing fuel pump shows many warning signs, which when identified at the right time, will avoid complete damage to the fuel pump. A few warning signs are quite clearly evident if the fuel pump is thoroughly checked – broken hoses, fuel leaks, discolored electrical terminals, burnt or bubbled plastic at the fuel pump fuse, etc.

There are a few other warning signs that are displayed by the vehicle itself. They are as follows:

Strange whining sounds: One of the early as well as the clear signs of failing fuel pump is the development of a high pitched screeching sound, when the engine is first engaged. However, the sound will slowly disappear after some time. Moreover, the sound produced by the failing fuel pump is not the same for every vehicle. It may vary based on the type of fuel pump. An early inspection, after the development of such strange sounds will help save the fuel pump from further damage.

Engine misfires: A failing fuel pump may cause engine misfires that in turn will cause the car to jerk occasionally. Engine misfires may happen quite often, most probably 3-4 times, and later the vehicle may run smoothly for many miles. This sign translates to the wearing out of the fuel pump, because it is unable to maintain a steady fuel pressure.

Problem in starting and accelerating: A failing or dead fuel pump may also prevent the engine from starting. If you are sure that the starter and the battery of your vehicle are good, and still you are facing a starting problem, then it is the sign of faulty relay. As already stated, faulty fuel pump wiring harness can result in improper power supply to the fuel pump, thus, resulting in sluggish acceleration and starting troubles.

Extended engine cranking time: In order to cool down the components of the fuel tank, maximum amount of fuel sent to the engine by the fuel pump will be returned to the fuel tank. An anti-drain back valve in the outlet of the fuel pump aids in this fuel returning process. Whenever the fuel pump stops functioning, the valve gets closed preventing the fuel from running back into the fuel tank. This condition can be identified by the extended cranking time while starting the vehicle.

Engine loses power: This sign of engine losing power can be typically seen when the vehicle is running at high speeds, especially when climbing hills. If you are sure that there is nothing wrong with the fuel filter, it is safe to assume that the fuel pump is failing.

On identifying the above issues in your fuel delivery system, it is better advised to get your vehicle checked by a good technician, who will further diagnose the issues by conducting fuel pressure and volume tests (through fuel pressure gauge), and the electrical checks (through digital volt & ohm meter). It is only after these tests, should you decide as to replace or fix your fuel pump.

Timely repairs or replacement of fuel pump will help you to solve the issues quickly. However, while replacing the fuel pump it is always better to opt for the best quality aftermarket products, offered by reputed dealers, to get more durable and better performing fuel pumps.