You’ve heard the saying, “With great power comes great responsibility,” right? The same thing is true for your high-performing engine. If you want more power, then you need more fuel pressure regulation.- Carbureted Fuel Pressure Regulator
For an engine to make more power, it needs copious amounts of fuel to create that power. A determining factor in adding horsepower to your engine is the amount of fuel it can burn over time. This makes a fuel pressure regulator a very essential component of your vehicle.
If your high-performance engine is making 450hp or more, a fuel pressure regulator is imperative to have an accurate set point.
Let’s take a look at the purpose and function of fuel pressure regulators for carbureted engines and how to know when they need replacing.
What is a Carbureted Fuel Pressure Regulator?
Mounted between the fuel pump and the carburetor, the carburetor fuel pressure regulator does just that: regulates fuel pressure. Its purpose is to ensure that the supplied fuel pressure stays within a predesignated range.
These regulators will have an intake port, a primary outlet, and a bypass port. Its job is to regulate the flow of fuel to the carburetor by allowing fuel to bypass it and return to the fuel supply tank.
Two Types of Fuel Pressure Regulators
Mechanical spring regulators and vacuum diaphragm regulators are 2 of the basic design types.
Mechanical Spring Regulators
These regulators have a spring that controls a diaphragm. The springs are at a set rate but can be adjusted to the tension on the internal spring by preloading it. Tightening the spring makes the fuel pressure go up while loosening it makes the pressure go down.
Vacuum Diaphragm Regulators
Vacuum-style regulators rely on vacuum pressure to open and close the diaphragm. Low idle vacuum levels open the diaphragm which allows the bypass for fuel to return to the supply tank. As the throttle is applied, the vacuum levels decrease in the diaphragm to maintain the fuel pressure to the engine.
How Does It Work?
When the fuel pump powers on, it sends that fuel to the carburetor and then to each cylinder. The fuel is pumped through the fuel lines, and often through a filter, to the fuel pressure regulator. The regulator then controls the bypass valve which opens and closes allowing fuel to get to the engine continuously.
Most carbureted fuel pressure regulators are designed with an inlet and outlet port. The inlet port feeds the carburetor, while the outlet port returns the fuel to the tank.
A fuel system with zero demand from the engine will be constantly cycling fuel through the pressure regulator to the bypass and back into the fuel tank. Once the engine begins demanding fuel, the return flow begins to slow as that fuel is now going to the carburetor.
As the demand increases through the rpm range of the engine from idle to wide-open throttle, your fuel pump continues to spin at the same speed. It steadily puts out the same amount of fuel while the fuel pressure regulator ensures that the carburetor has had the precise fuel pressure it needs to function at peak efficiency.
Any drop in fuel pressure means that you do not have enough fuel in your carburetor, and are at risk of damage due to low fuel pressure. Lowered fuel pressure can sometimes cause catastrophic failures like melted valves or pistons putting your entire engine out of commission.
How To Test Your Fuel Pressure Regulator
The first step in testing the efficiency of your fuel pressure regulator is to check the vacuum hose. If the hose connection is tight, it should be working properly. If the hose is loose, examine its condition and then disconnect it from the regulator.
If you find fuel in the vacuum pressure line, your fuel pressure regulator will need to be replaced.
A fuel pressure gauge will also help you diagnose any problems related to the fuel pressure regulator. A simple fuel pressure gauge can be plumbed into the fuel line to see how much pressure is getting to the carburetor.
Check the fuel pressure gauge while the engine is running and when the engine has been turned off. Fuel pressure should hold to specs while the engine is running. With the engine off, pressure should hold for about 5 minutes.
How Do I Know When the Carbureted Fuel Pressure Regulator Needs to Be Replaced?
When your fuel pressure regulator is bad, the diaphragm cannot open or close. There are several symptoms your vehicle will begin to display when it requires repair or replacement.
- Engine misfires
- Check engine light comes on
- Fuel leaks from the tailpipe
- Noisy fuel pump
- Difficulty with acceleration
- Black smoke coming from the exhaust
- Black spark plugs
- The engine won’t turn over
- Gasoline in the vacuum hose
- Reduced fuel mileage
If your vehicle is showing one or more of these symptoms, inspecting the function of your fuel pressure regulator would be a good place to start in diagnosing the problem.
Where Can I Find the Best Carbureted Fuel Pressure Regulators?
The higher pressure carbureted setups must have the best quality fuel pressure regulator available. JEGS offers a large variety of regulators made by the industry’s leading manufacturers for both carbureted and fuel injection systems.
A family-owned and operated company, JEGS has been in business since 1960, supplying high-performance parts to car lovers everywhere who are obsessed with making even faster hot rods.
Regulate Your Fuel Pressure
The unrivaled expertise of JEGS High Performance is just a click or a phone call away. If you need to verify the exact fuel pressure regulator you need, their experts are standing by to answer all of your questions before you make your purchase.
Even with the supply and shipping challenges we face today, most parts will ship to you the same day allowing you to get back to work on your car, back on the road, and back in the race in no time.
