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How To Fix High Fuel Pressure

Do you have a problem with high fuel pressure in your car? High fuel pressure is a common problem for many vehicles and can lead to excessive consumption of fuel. We have researched the best method to fix it, and now we'll share our findings.

There are three main parts that you should look into when looking for the possible cause of high fuel pressure. These are the following:

  1. Fuel pressure regulator
  2. Return line
  3. Fuel line couplings

Knowing how to troubleshoot these parts is very important in finding the cause of high fuel pressure. Each of these parts will be discussed in more detail so that you can understand what the problem is and what your next steps should be so read on!

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Common Signs and Symptoms of High Fuel Pressure

  • Check engine light
  • Gasoline smell coming from the exhaust pipe
  • Poor fuel economy
  • Engine overheating
  • Wet spark plugs due to engine flooding
  • Blackened spark plugs

What To Do When Your Car Has High Fuel Pressure

Fuel pressure of a car engine

If you have noticed that your car has been running higher than normal fuel pressure, you probably want to know what causes high fuel pressure and what you can do about it. Here are the three most likely causes of high fuel pressure:

Bad fuel pressure regulator

High fuel pressure can be caused by a faulty fuel pressure regulator. When a fuel pressure regulator is stuck in the closed position, the flow of fuel to the combustion chamber is restricted.

This results in the fuel pump having to work harder to force the fuel through the fuel line, thus the increase in fuel pressure. It's like putting your thumb over the end of a garden hose. The increase in fuel pressure will cause the car to run rich.

How to replace a bad fuel pressure regulator

Before you start, it's highly recommended that you take pictures or a video as you disassemble the fuel pump and take note how the parts fit together. Doing this will help you easily put everything back together.

Here are the steps:

  1. Locate the fuel pressure regulator in your car. Some cars have them in the fuel pump itself (for carburetor engines) or you can find them at the end of the fuel rail (for fuel-injected engines).
  2. If the fuel pressure regulator in your car is inside the fuel pump, remove the wirings so you can take the fuel pump apart.
  3. Detach the rubber hose and the fuel pressure regulator. While you're at it, you might as well replace the filter of your fuel pump.
  4. Install the new fuel pressure regulator and attach the rubber hose. It is recommended that you use a new rubber hose.
  5. You may have to heat both ends of the rubber hose so you can easily fit it into the fuel pressure regulator.
  6. Apply oil to the fuel pressure regulator's O-ring.
  7. Clean and put the two pieces of the fuel pump back together.
  8. Put the wirings back on and put the fuel pump back into the fuel tank.

If you haven't seen a fuel pressure regulator before, it is a small, cylindrical metal device that looks like a nozzle attachment with a rubber hose attached to it. You'll find this type of fuel pressure regulator in carburetor engines.

Others may look different and they may even have a built-in pressure gauge. They're mounted after the fuel rail. You'll find this on most fuel-injected engines.

Clogged return line/fuel line couplings

Return lines may become clogged with dirt over time. This can restrict the movement of fuel back to the gas tank. As a result, the pressure inside the return line rises, which increases fuel pressure.

How to fix clogged return line/fuel line couplings

You can detach the return line and put some penetrating oil into it. Blow it with compressed air from the tank end of the hose to force the clog out of the line.

In case, you don't know where to find the return line, it's the hose that's one size smaller than the fuel line, which you'll find on top of the fuel injector rail after the back-pressure regulator. If the problem is in the fuel line couplings, replace them.

What is the Main Reason Why Fuel Pressure Regulators Fail?

Over time, daily wear and tear will eventually lead to a failure of the regulator. A fuel pressure regulator that is stuck in a closed position will cause an increase in fuel pressure. This will cause your engine to run richer, which will lead to poor fuel economy and engine misfiring. 

On the other hand, a fuel pressure regulator that is stuck in an open position will cause a decrease in fuel pressure.

Low fuel pressure will cause the engine to misfire and run lean. Since the engine is running lean, there's not enough fuel to provide sufficient combustion. When this happens, you'll notice a significant reduction in your car's power. 

Adjustable Fuel Pressure Regulator for race car

How Long Can I Expect My Car's Fuel Regulator To Last?

The life expectancy of a fuel pressure regulator depends on many factors, such as how often the vehicle has been driven, how hard it's been driven (road conditions and driving habits), and how the vehicle has been maintained.

If you're expecting to find an expiration date stamped on the fuel regulator, it's probably not going to be there. You have no way of knowing for sure how long a car's fuel pressure regulator will last, but with proper care and maintenance, they're designed and intended to last as long as the car does.

When Are Signs That I Should Replace My Car's Fuel Pressure Regulator? 

Fuel pressure gauge

A fuel pressure regulator is designed to maintain the appropriate pressure in the engine's fuel system. However, fuel systems will become prone to leaks due to age, wear and tear, exposure to elements, and other factors.

As such, the fuel pressure regulator should be replaced whenever you see these signs:

Exhaust pipe dripping gas

The amount of oxygen and the amount of fuel injected into the combustion chamber are carefully monitored and adjusted to maintain the proper air-fuel ratio.

If the air-fuel ratio becomes too rich, the engine may not effectively burn the fuel. This results in excess fuel that is merely excreted as waste material through the exhaust pipe rather than converted into useful energy.

Since the engine is burning octane purely, the engine will have a higher-than-normal operating temperature and may overheat. 

Exhaust pipe emitting black smoke

You can always count on a bad fuel regulator to ruin your day. The first time you start your vehicle, you won't notice anything out of the ordinary. However, as you drive the car for longer periods of time, you will notice black smoke emanating from your exhaust. 

Black smoke emitted by your exhaust pipe means that there is something wrong with your fuel injection system. It could be anything from a bad fuel injector injecting too much fuel to a bad intake valve not allowing enough air to get in.

In most cases, it's the fuel pressure regulator that is the culprit. Further, A bad fuel regulator will allow too much gas to enter the engine and create a lot of carbon monoxide and burnt hydrocarbons. This will result in the car emitting black smoke.

Electronic Fuel Injection Bypass Regulator

How Much Will It Cost Me to Have My Car's Fuel Pressure Regulator Replaced by a Mechanic?

Typically, it will cost you between $250 to $350. However, as we have shown previously, replacing a pressure regulator is usually a very quick and easy project. This is because fuel pressure regulators are built into the fuel system, which means they are fairly easy to get to and replace.

All you need to do is to get an appropriate replacement fuel pressure regulator, which you can find at your local dealer or online. Once you have the part, simply remove the old part, connect the new one, and reattach the return line. 

However, if you don't want your hands dirty, you can ask a mechanic to replace the part for you. You will have to pay for their labor, which can add up.

What is the Easiest and Fastest Way to Check Fuel Pressure Without a Gauge?

The most convenient way of checking fuel pressure without a gauge is through an OBD II scanner. You don't have to know about psi (pound per square inch) or any nerdy stuff of that sort. Simply plug the scanner into the OBD II diagnostic port in your car under the dashboard and it will immediately tell you whether there is a problem or not.

Error code that indicates an issue with the fuel pressure regulator:

Check out this OBD II scanner on Amazon.

Can I Still Start My Car Even If the Fuel Pressure is High? Is It Safe?

Fuel regulator gage with aluminium spare tank on racing car engine

The short answer is yes. However, you may experience occasional sputtering due to uneven fuel and air distribution caused by high fuel pressure.

Your car will also run rich, which means you'll have more gas and less air than the amount you need for proper combustion. In addition, running rich will give you a greater chance of clogging up your catalytic converter.

What's the Normal Fuel Pressure for Cars?

Car fuel pressure test by using a fuel pressure gauge tester, How To Fix High Fuel Pressure

The fuel pressure can vary greatly depending on the type of engine. If you have a fuel-injected engine, you should have a normal fuel pressure between 50 to 60 psi. An engine with a carburetor fuel system is good with 5 to 7 psi.

In Closing

Car fuel pressure test by using a fuel pressure gauge tester

There is no doubt that fuel pressure can be a bit tricky to deal with. However, we have researched a few methods to help you with this. The first step to fixing high fuel pressure is to ensure that you have a good idea of where the problem is. Most of the time, high fuel pressure is caused by an issue with the fuel pressure regulator. Nevertheless, knowing how to diagnose and repair high fuel pressure in your car will help you save time and money.

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