Do you depend on a portable gasoline-powered generator to keep your major appliances running when your home experiences a power outage? Then there’s the potential for that generator to leak fuel, a frustrating occurrence that can severely compromise the equipment from fully doing its job. Repair Clinic has identified the four most likely locations where your generator may develop a fuel leak and what you can do to fix the problem. We’ll get to those in a moment, right after a refresher on how a gas-powered generator works.
How a gas-powered generator creates electricity
Most gas-powered portable generators rely on a four-cycle engine. Similar to an automobile engine, a four-cycle engine draws gasoline from its fuel tank and has a separate sump for oil. Four-cycle engines may have an electric start feature that allows the engine to be turned over by using an ignition key or a start button, or the operator may need to pull a starter rope to accomplish this.
How the ignition process begins
When the start button is pressed, the ignition key turned, or the rope is pulled, the starter engages the starter cup on the flywheel and rotates the crankshaft. The rotating crankshaft connects to the piston which moves up and down within the cylinder and the ignition process begins. The flywheel has permanent magnets built into it, and as it rotates past the ignition coil, a magnetic field is created. The magnetic field induces electricity, allowing the ignition coil to send voltage to the spark plug.
A four-cycle engine has four strokes
The piston will travel down the cylinder creating a vacuum that draws fuel and air through the carburetor where they mix before entering the cylinder through an intake port. This action is called the “intake stroke”. Next, the “compression stroke” takes place as the piston travels back up to the top of the cylinder and the intake valve closes. The spark plug now fires and ignites the fuel and air mixture which forces the piston down (known as the “power stroke”). The momentum of the spinning flywheel provides enough force to push the piston back up. The exhaust valve will then open, and the combustion gasses will exit through the muffler in what is the fourth and final cycle – the “exhaust stroke”. A four-cycle engine will continue to run and repeat these four cycles until it is turned off.
How the generator generates voltage
A typical portable gasoline-powered generator engine will have a top speed of 3750 RPM with no load applied. This type of generator type will use a rotor, stator, voltage regulator, and brushes to generate 120 volts of alternating current, 240 volts, or both. The rotor is essentially a magnet that rotates inside of a conductor, such as a copper coil, to create a magnetic field that induces current. The stator will often have three main copper coil windings: the excitation winding plus two voltage output windings that create the rotor’s magnetic field. The excitation winding sends voltage to the rotor through the voltage regulator and brushes. By increasing or decreasing the voltage applied to the rotor, the generator controls the voltage of the output windings.
The voltage regulator converts voltage from AC to DC
The voltage regulator converts the voltage sent to the rotor from alternating current (AC) to direct current (DC). The regulator will monitor the output winding voltage as well. The regulator has a preset “reference” voltage that the output windings should produce. In North America, that voltage is 120 volts of alternating current at 60 Hertz. If the generator’s output voltage is too low, the regulator increases the direct current voltage being sent to the rotor to strengthen the rotor’s magnetic field. Conversely, if the output voltage is too high, the regulator will decrease the direct current output to the rotor to weaken the magnetic field.
Where the generator’s gas leak is likely coming from
If your gas-powered generator is leaking fuel, here are the four most likely locations to inspect along with some helpful tips to resolve the leak issue:
- Worn engine carburetor bowl gasket – Inspect the engine carburetor to see if you can detect a fuel leak. If fuel is leaking out, then it’s likely the carburetor bowl gasket is worn out or missing. You can install a new gasket to provide a proper seal for the bowl to stop the leak.
- Defective float assembly – Various float assembly components inside the carburetor bowl could be defective as well. The float needle opens and closes the float valve to allow fuel to enter the bowl. If the float needle or the float itself is damaged, the carburetor may continue to fill with fuel until it overflows. You should be able to stop the leaking by replacing one or more of these components. If several float assembly components appear worn, consider purchasing a generator engine carburetor repair kit.
- Leaking fuel line – One or more of the fuel lines may have developed a leak as well. While it may be tempting to try to patch the line, or trim the damaged section and then attempt to stretch the line to attach it to the nearest valve, this approach is not recommended. Repairing a damaged line will likely lead to the failure of the line the next time you need to fire up the generator, so it’s best to replace a leaky fuel line with a brand-new one.
- Damaged fuel tank – Last, but certainly not least, you should inspect the place where the gasoline prepares for its journey to the generator’s engine: the fuel tank. Does the tank have any cracks in it? Any small holes? Then it’s time to replace the gas tank with a new one (attempting to patch up the old tank is not recommended).
Need to replace some carburetor components to fix your generator gas leak? Or maybe you need to install a new fuel line or fuel tank? Repair Clinic strongly encourages you to use only genuine original equipment manufacturer (OEM) parts when doing the repair. Genuine OEM parts are manufactured to be compatible with your specific generator model to ensure the unit is fixed right the first time. To find the right OEM part for your generator, enter the full model number of the generator, or the generator’s engine, into the Repair Clinic website search bar. You can then use the “Part Category” filter (Example: “Engine”) and the “Part Title” filter (Example: “Fuel Tank Fitting”) to identify the exact part you need. Repair Clinic stocks portable generator parts for all the top brand names such as Black Max, Briggs & Stratton, Cub Cadet, Generac, Homelite, Honda, Husky, Kawasaki, PowerStroke, Ryobi, Toro, Troy-bilt, among others.
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