6 Symptoms of a Bad Fuel Pressure Regulator
Fuel injectors receive pressurized fuel from the regulator, spraying the proper amount into combustion chambers. This key component governs both fuel quantity and pressure. But regulators can still fail over time. In this article, we’ll cover the most common symptoms of a bad fuel pressure regulator and its average replacement costs so you know what to expect.
Top 6 Bad Fuel Pressure Regulator Symptoms
A properly functioning fuel pressure regulator is important for consistent, reliable fuel delivery in a vehicle. Without precise regulation of fuel pressure, the delicate combustion process powering the engine falls into disarray. Below are some 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. 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.
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.
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.