6 Symptoms of a Bad Fuel Pressure Regulator (and Replacement Cost)

Last Updated on January 22, 2020

Fuel injectors supply the combustion chamber of the engine with the proper amount of fuel it needs for combustion with air. The fuel is distributed to the injectors through the fuel pressure regulator.

This regulator not only manages the amount of fuel that gets sent to the injectors, it also manages the pressure of the fuel as well.

You could basically call this a fuel management component of the engine and it exists in all vehicles which have internal combustion engines. Like any automotive component, it may fail at some point so knowing the symptoms of a bad fuel pressure regulator is important.

How a Fuel Pressure Regulator Works

The driving conditions that your vehicle is under determines how much fuel is required to be sent to the combustion chamber.

In order to get the proper amount of fuel sent, the fuel pressure regulator has mechanical diaphragms that are operated with a vacuum which changes the fuel pressure to the necessary amount for delivering the fuel.

Some new vehicles now have electronic fuel pressure regulators rather than the mechanical ones.

See Also:  Symptoms of a Bad Fuel Rail Pressure Sensor

Top 6 Bad Fuel Pressure Regulator Symptoms

It is important that a vehicle has a properly working fuel pressure regulator for dependable fuel delivery.

If the regulator were to ever become faulty or malfunction in some way, it would disrupt the entire internal combustion process which the engine depends on to generate moving power for the vehicle.

There would be a number of easily noticeable symptoms that would arise if your fuel pressure regulator were to go bad or be damaged. Below are seven of the most common signs of a faulty fuel pressure regulator.

#1 – Engine Misfires / Weak Acceleration

The most obvious symptom of a bad fuel pressure regulator is an engine misfire and loss of acceleration power. You will be driving and then suddenly your vehicle will lose power, stumble, and/or slow down.

Then it may go back to accelerating normally for a short time before losing acceleration power again. This is obviously not something you want to put up with because it can be very dangerous when you’re driving on the road.

#2 – Spark Plugs Covered in Soot

If you suspect that you have a bad fuel pressure regulator, take out a spark plug and see if there is any black soot on the end of it. If there is, then a faulty fuel pressure regulator is a possible cause among other things.

Make sure to check the ends of all other spark plugs for soot as well. This soot is the result of oil burning in the engine’s head. You will need to replace both the fuel pressure regulator and the dirty spark plugs in this case.

#3 – Black Smoke

You should only be seeing a bit of white smoke coming out of your tailpipe if your vehicle is warming up. If you start seeing dark gray or black smoke, the possible cause can be attributed to a bad fuel pressure regulator.

Although there are lots of other reasons why black smoke is coming out of your exhaust, it is likely the regulator’s fault if you notice a combination of other symptoms listed here as well.

#4 – Fuel Dripping Out of Exhaust

While rare, if your tailpipe is dripping gasoline out of it, then your fuel pressure regulator is probably letting it happen because it has gone bad. A malfunctioning regulator may allow some gasoline to get into the vehicle’s exhaust system. From there, a bit of it may find its way out of the tailpipe along with the exhaust fumes.

Before you suspect this, make sure you simply don’t have water coming out of your exhaust in the form of condensation. In this case, a bit of water is usually completely harmless.

#5 – Vacuum Hose Has Gasoline

One sure way to find out whether you have a bad fuel pressure regulator is to disconnect your vacuum hose from your fuel pressure regulator and see if it has gasoline inside of it. Be sure to do this while your engine is turned off.

If there is gasoline in your vacuum hose, then you have a bad fuel pressure regulator that leaks.

#6 – Engine Won’t Turn Over

If you try to start your vehicle and it won’t start because the engine doesn’t turn over, then your issue is likely a drained car battery or a bad starter motor. But it can also mean something is wrong with your fuel pressure regulator.

Since the regulator is what manages the fuel pressure and fuel is needed when starting a car, naturally a bad regulator can prevent the engine from starting.

When the fuel pressure regulator first starts going bad, you may be able to start your vehicle after multiple attempts. But if the regulator never gets replaced, it will eventually get to the point where you won’t be able to start your car at all.

Fuel Pressure Regulator Replacement Cost

The cost to replace a fuel pressure regulator depends on two main things. Is it a standard manual driven regulator or an electronic one? And how hard is it to get to?

In most cases, the part itself will cost you around $50 to $200 but for vehicles with an electronic fuel pressure regulator, you can easily pay double that.

Most of the time, the fuel pressure regulator is located in a fairly easy to access location so time spent replacing it isn’t too much. Expect to pay somewhere in the range of $100 to $150 for labor (more if other components like the fuel rail needs to be removed as well).

All together, the total cost of a fuel pressure regulator will run somewhere between $150 to $350 in most cases but it can easily go above $500 for electronic fuel pressure regulator replacement. To save money, it’s recommended to have an independent mechanic or repair shop do the work versus a dealership.