Can a Bad Fuel Pump Relay Cause Misfire?

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Can a bad fuel pump relay cause misfire? Apparently, to answer this question perfectly, we will need to understand the term “Engine Misfire” and its causes.

Engine misfire occurs when one of the cylinders lacks combustion; this will now cause the car to shake for a moment.

Each time your car engine misfires, you’ll notice a shake or quick hesitation, which is not normal. Misfiring can be dangerous and can get you so worried.

Things that could cause engine misfiring include bad sensors, faulty fuel delivery systems,  mechanical faulty, and many other reasons.

To fix engine misfiring, you have to indicate the cause and fix it. The best way to discover the fault is by using an OBD2 scanner.

Can a Bad Fuel Pump Relay Cause Misfire?

The fuel pump relay is part of the fuel systems, which works in hand with other components for the engine to function.

Apparently, when this relay goes bad or is faulty, it could cause the engine to misfire due to an insufficient supply of fuel to the engine.

Notwithstanding, there are many other possible causes of engine misfiring. Thus, it is important that you find out the exact reason why your engine is not performing as usual. When the faulty component is identified, you can go ahead to fix it.

But, if you don’t troubleshoot to find out the exact faulty component, you may end up fixing the wrong component; thus, the issue would still persist.

To make everything easy for you, this article highlights the causes of engine misfiring and also explains the symptoms of a bad fuel pump relay.

What Are The Causes Of Engine Misfiring?

There are many reasons why your engine is misfiring; however, these ones listed below are among the commonest ones experienced by most drivers.

1. Emissions Equipment Issue

In some modern cars, you will find different emissions equipment, and they are all available to minimize carbon release.

This equipment can include the Positive Crankcase Ventilation system (PCV) and the Exhaust Gas Recirculation system (EGR). Any bridge in any of these systems can cause misfiring.

2. Faulty Ignition System

The ignition system comprises a lot of components, including spark plugs and the crankshaft position sensor.

If any of these components of the ignition system begins to malfunction, chances are that you’d experience engine misfiring as you drive.

3. Damaged Delivery System

Fluids, liquid, and gas are transmitted through mediums to get to the engine and other necessary systems where they are needed to trigger different actions. 

The mediums through which these substances move to get to their destinations are called the delivery systems.

Typically, every car has air and fuel delivery systems. When any of these systems is faulty, it implies that the engine will lack sufficient supplies of the necessary fluid needed to move a car, and thus, you may experience misfiring.

4. Faulty Sensors or Modules

Automobile components and systems communicate using sensors, wires, and modules. A bridge in communication – caused due to a bad sensor or module – can lead to frequent misfiring.

More so, bridged circuit connections and faulty mechanical components can all lead to misfiring.

Signs Of A Bad Fuel Pump Relay

When your fuel pump relay goes bad, one of the first signs you’d notice is the illumination of the check engine icon on your dashboard.

Yes, there are many situations that can cause the check engine light to come on; however, it is important to say that a faulty fuel pump relay is one of those “many situations.”

Other signs of a bad fuel pump relay include:

  • Engine stalling
  • Your car frequently goes off while driving
  • Your car makes no noise when you start (if the relay is working, you should hear a smooth whining noise as you start the car).
  • Loud winning noise when you start the car (a bad fuel pump can trigger a “very loud” noise, while a good one will only make little noise to prove that the system is working fine).
  • Inability to start your car (a faulty relay starves the engine of fuel; thus, your car won’t start)
  • Engine misfire


So, “can a bad fuel pump relay cause misfire?” Yes, it can cause misfiring since it is connected to the fuel pump, and any damage to the fuel pump system can starve the engine of sufficient fuel needed to make a car move.

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