Engine Too Low On Power A weak Fuel Pump is usually accompanied by certain symptoms that you can notice when helping the engine and fuel delivery. Catching these signs earlier can save you from causing more harm to the fuel system, in turn saving on expensive repairs (500USD – 800USD if replacing pump).
One of the most common signs of a weak fuel pump is difficulty starting the engine. If the fuel pump has difficulty getting enough pressure (most engines require somewhere between 30 and 80 psi) it will take many engine cranks to fire up or not at all. According to ASE-certified mechanics, 1 in every 5 vehicles brought in for a starter problem has an underlying pump issue.
Another sign is loss of power when you accelerate or under load. If the engine requires a high surge of fuel, as when climbing a hill or passing on the freeway, an undersized or weak pump may not supply enough. And that leads to hesitation, sputtering, or stalling. Research has shown that fuel pumps functioning at 70% of their rated capacity can have dramatic effects on performance (particularly for high-output engines).
The less apparent but also arduous symptom is when the vehicle returns low fuel economy. An anemic pump creates a vacuum for the ideal air-fuel mixture, making the engine needlessly rich in its combustion. Mileage may drop 10–15% (more in the city). If a failing pump is the cause, this can be pinpointed by routine inspections and tests of the fuel pressure.
The fuel tank may make strange noises such as whining or humming when the pump is worn out. A healthy pump will run almost silently while a weak or struggling to maintain pressure will emit high-pitched noises. Pump noise complaints account for 15% of fuel system diagnostic cases, so a little prevention can go a long way according to AAA.
A fuel pressure test tells you if the pump is working and providing sufficient pressure. With the engine idling and then revved, mechanics use a gauge hooked up to the Schrader valve to measure pump output. Weaker pump (20 psi in a system that requires 50 psi).
In fact, an indication that the pump is failing can be electrical issues, like drops in voltage. Using a multimeter to test whether the pump is receiving 12 volts from the electrical system If you know the pump draws 11 volts or more but is reading lower, that is almost always a wiring or relay issue — one that will quickly kill the pump if not resolved.
To keep the pump from clogging, replace the filter every 20,000 to 30,000 miles. Regular system cleanings and inspections as part of preventive maintenance help ensure that pump failures are rare. By investing in a quality Fuel Pump and one that responds to symptoms, it can ensure reliable performance and longevity of the entire fuel system.