Fuel Pressure Regulator: Functions, Bad Symptoms and Replacement Cost

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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.

Basic Functions

The driving conditions that your vehicle is under will determine the amount of stress that is put on the engine. These conditions determine how much fuel is going 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. Many new vehicles now have electronic fuel pressure regulators rather than the mechanical ones.

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Top 6 Bad Symptoms

It is important that a vehicle has a properly working fuel pressure regulator to keep it moving steadily and consistently. 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 once your fuel pressure regulator goes bad or starts to go bad.

Below are the top 7 symptoms of a bad 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 stumble, sink 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 your spark plug and see if there is any black soot on the end of it. If there is, then you likely have a bad fuel pressure regulator. If your vehicle has any more spark plugs, check the ends of those 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 spark plugs in this case.

3) Black Smoke – You should only be seeing gray or white smoke coming out of your tailpipe. If you start seeing black smoke, the cause can likely be attributed to a bad fuel pressure regulator. Although there are lots of other reasons why black smoke may be there, it is likely the regulator’s fault if you notice any of the other symptoms listed here too.

4) Tailpipe is Dripping Gasoline – 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 will allow gasoline to get into the vehicle’s exhaust system. From there, it will find its way out of the tailpipe along with the exhaust fumes.

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.

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 something is wrong with your fuel pressure. Since the regulator is what manages the fuel pressure, then your fuel pressure regulator is to blame and must be replaced. In the beginning, you may be able to start your vehicle after multiple attempts at trying to turn over the engine. But if the regulator never gets replaced, then you will eventually not be able to start your engine ever.

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Replacement Cost

The replacement cost of a fuel pressure regulator will vary, depending on the make and model of your vehicle. For the average passenger vehicle, you can expect to pay anywhere from $100 to $350 for a new fuel pressure regulator. The labor costs will be from $70 to $150 while the parts costs will be from $30 to $200. If you are experienced in basic auto work, then you could save yourself from having to pay the labor costs by doing the replacement job yourself. Otherwise, you can expect to pay an extra $100 for the labor. Also, don’t forget about the taxes and fees which will be added to these prices as well. The exact amount of the taxes and fees will depend on the regulatory tax laws of your location.


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