Intank fuel pumps: why they go bad

Fuel pumps do not just die. Their death is caused by reasons like dirty fuel, low fuel, bad filter, faulty fuel pressure regulator and fuel lines.

The fuel pump is one part of a car many owners replace at least once in the lifespan of a car. Sometimes, the failure repeat often due to the root cause not treated.


Below are the top reqsons why fuel pumps become faulty.


1. Fuel contamination

Corrosion, moisture, debris are common fuel contaminants. Moisture causes corrosion of the fuel pump and debris cause restriction at the fuel pump and filter. This can be from a contaminated gas put in the car.


2. Clogged filters/strainers

Corrosion and other debris cause the strainer to be blocked, thereby restricting fuel flow. Normal flow of fuel helps the cooling of the pump and when the flow is reduced, it overheats, shortening its lifespan.


3. Electrical faults

This ranges from melted wires, burnt connectors, partial contacts, bad ground. These create either low voltage condition or high current surge that can cause the fuel pump to heat up and damage it.

If the voltage is low, the current draw will rise in order to deliver required amount of fuel. This current rise causes rise in temperature of the windings and in turn causes premature failure of the fuel pump.

4. Insufficient filtration

When the filter is old or is clogged by debis or a wrong type of filter is used, debris can find their way into the fuel pump and this will damage the fuel pump.


5. Brushes of the motor wearing out

As the fuel pump ages, the brushes will gradually wear and give way after a period of use. This will certainly cause it to stop working and brushes of fuel pumps are not normal replacement parts.


6. Restriction in inlet and outlet of the pump

Anything that causes restriction at the suction side (inlet) can cause cavitation which will reduce lubrication and cooling of the fuel pump.


7. Faulty fuel pressure regulator

A faulty FPR might not allow fuel to return to the tank and this will increase the pressure on the outlet line of the fuel pump, causing it to be overworked.


8. Faulty return line

Normally, fuel from the return line is directed into the fuel pump housing where the fuel pump sits. This helps to cool the fuel pump and also ensure that the fuel always have enough fuel to suck in. It also does the task of lubrication. When there is no fuel from the return line, the fuel pump can momentarily suffer fuel starvation and insufficient cooling.


9. Faulty fuel pump housing

One of the functions of the fuel pump housing is to ensure that there is sufficient fuel for the fuel pump to take in and also to make the fuel pump sit in fuel for adequate cooling and lubrication even when the fuel in the tank is low. When the housing is broken or not present, the fuel pump can easily suffer fuel starvation and overheat.

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