4 Causes of Fuel Pump Misdiagnosis

Some hobbyists may rush to replace the fuel pump in their cars under the mistaken belief that the pump has malfunctioned when the fault was elsewhere. This article discusses some of the defects or situations that may lead an inexperienced car owner to think that the fuel pump is defective.

Poor Strainer Installation

Some people may install a strainer on the inlet side of the fuel pump. Improper installation can cause that strainer to get in the way of the float arm of the fuel sensor. Consequently, the gauge on the dashboard may give an incorrect reading of the amount of fuel in the tank. You will therefore mistakenly think that your engine has stalled because of a defective pump when the reality is that the tank is empty and the fuel sensor is providing wrong data.

Muted Pumps

You may also be misled into thinking that your fuel pump is defective if you replaced it with a newer version that operates silently. Many conventional fuel pumps emit some noise in the initial seconds after an engine has been started. That noise signals that the pump is working to purge any air that was in the fuel lines before fuel starts flowing to the engine. Pumps that perform this role silently may therefore cause you to think that your pump is failing.

Faulty Relay

The fuel pump uses electrical power to work. This current can reduce in case the relay controlling the provision of power to the pump weakens. The pump may therefore fail to send as much fuel to the engine as required if it is getting insufficient power from the relay switch. Hurrying to condemn the pump as defective may therefore result in the needless expenditure of money on a replacement pump.

Defective Airflow Sensor

Your vehicle may stall or show other signs of limited fuel due to a defect in the sensor which provides information about the air entering the engine for combustion. For example, the sensor may be dirty. The dirt can affect the accuracy of the information that is sent to the engine's control module. Consequently, the air/fuel ratios will not be proper and the vehicle may stall or surge as you drive. Defective fuel pumps also cause these symptoms. Rule out airflow issues before you conclude that your fuel pump is defective.

As you can see, several faults can affect the performance of the fuel pump in your car. Ask an experienced mechanic to inspect and use diagnostic tools to identify the exact fault so that you can replace the pump only when it is necessary.