When your lawn mower isn’t getting the fuel it requires, it will begin running rough and sluggish. It may not even start or run at all. If you’ve narrowed your problem down to the fuel system, there aren’t too many items that will cause a lack of gas.
A SCAG lawn mower isn’t getting gas when there is old gas in the fuel system, the fuel filter is plugged, the fuel line is clogged, the fuel pump is bad, the carburetor is dirty or the fuel cap is bad.
Go through the fuel system using the steps listed below. If you find your starting or running problem isn’t actually due to a fuel problem, check out my guide on “Reasons a SCAG Lawn Mower Won’t Start” for other causes that can mimic a fuel problem.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
6 Reasons Your SCAG Lawn Mower Isn’t Getting Fuel
Bad Fuel
Gasoline will break down and become less effective. Most gasoline contains a product called ethanol. This is an alternative plant-based fuel added to make gasoline a little more environmentally friendly.
While ethanol is fine to run in most vehicles, it is not good for the small engine used in your SCAG mower.
Because of this, use gasoline that has a low ethanol content or an ethanol-free fuel. When choosing gasoline for your gas-powered mower, use unleaded gasoline with a minimum octane rating of 87 and a maximum ethanol content of 10%.
This is often sold as E10 or regular fuel. Read the label on the pump to verify the octane rating and ethanol content. Read more about the right gas to use in a SCAG here.
Ethanol attracts moisture to the fuel. This water and ethanol mixture can leave behind gummy deposits and cause corrosion of the fuel components.
Because gas breaks down as quickly as 30 days after purchase, it’s important to consume the fuel within this time period. When you have more fuel than you can consume, add a fuel additive to stabilize the fuel.
Solution: Use a fuel siphon pump to drain the old fuel from your tank. Collect the fuel in an approved fuel container so you can later recycle it.
Add fresh fuel along with a fuel additive to stabilize the fuel, reduce moisture and clean the fuel system. I use Sea Foam Motor Treatment in my lawn mower. You can read more about the advantages of Sea Foam here.
Plugged Fuel Filter
A plugged fuel filter can prevent gas from flowing through the filter restricting the amount of fuel the engine receives. The fuel filter should be replaced annually and more often when the fuel is dirty.
Solution: Replace your fuel filter when you find it is plugged. Turn off your fuel supply and remove the old filter. Use the arrow on the side of the fuel filter when installing the new filter.
The filter must be placed between the fuel lines with the arrow pointing in the direction of the mower’s fuel flow.
Clogged Fuel Lines
There are plenty of places for gummy deposits to stick to when flowing through the fuel lines. The flow will be compromised when these gummy deposits or dirt clog the lines.
To find a clog in the fuel line you will have to check each section of the fuel hose to make sure there is good flow and no restrictions.
Stop fuel flow using the fuel shut-off valve or pinch pliers to crimp the hose. Identify a section of the fuel hose you want to check. Remove the end of the line furthest from the fuel tank and place it in a container.
Start the fuel flow and confirm you are getting good flow into the container. Stop the fuel flow and reattach the hose if you are getting good flow.
Solution: If you aren’t getting good fuel flow, remove the section of the line from your mower. Your fuel supply should be shut off so you don’t end up with a fuel spill.
Spray carburetor cleaner into the line to help loosen the clog. Follow this by blowing compressed air through the line to remove the blockage.
Repeat using the carburetor cleaner and compressed air until the fuel line is clear. If you are unable to remove the restriction or if you find the line is dry and cracked, replace the fuel line with a new line of the same length and diameter.
Bad Fuel Pump
SCAG lawn mowers use a fuel pump to get fuel from the fuel tank to the carburetor which sits higher than the tank. Fuel cannot flow uphill with a pump.
Most SCAG mowers use a vacuum-style fuel pump that builds pressure off the crankcase to get fuel to the carburetor.
Some models use an electric fuel pump that uses power to operate. The pump can fail, but it may just be a lack of power to the fuel pump causing it to not function.
This can be due to a bad fuse, relay, or module. Use a multimeter to make sure you are getting a good connection and power to the pump before testing the pump’s function.
When the fuel pump cracks or fails to work correctly you will have to replace it. If you don’t see physical cracks or fuel leaking, you must take some troubleshooting steps to isolate the problem to your fuel pump.
Solution: Before you check your fuel pump, check to make sure you are getting fuel to the fuel pump. You may have completed this step already if you checked your fuel lines and filter for blockages, but if you didn’t, you need to start there.
Once you have confirmed fuel flow to the pump, remove the fuel line from the carburetor and place it in a container. Check your pump is working correctly by starting your fuel flow and starting your mower.
You should have a steady or pulsating flow of fuel coming out of the fuel line. If you do not, you need to replace your fuel pump.
If your SCAG mower uses an electric fuel pump, use a pressure gauge, to measure the fuel pressure. Make sure it is meeting the specification listed in your operator’s manual. If it is not, it’s time to replace the fuel pump.
Dirty Carburetor
The carburetor is a mechanical device that regulates the amount of fuel allowed to mix with air to create combustion in the cylinder.
When the carburetor is dirty, it can gum up, stick and no longer function properly. The engine in your SCAG mower isn’t able to get the correct amount of gas it needs.
Solution: First, identify whether you need to take your carburetor apart to clean it. Confirm you are getting fuel to the carburetor. If you are not getting fuel, check for restrictions in the fuel line, fuel filter, and fuel pump.
Next, remove your air filter and spray carburetor cleaner into the air intake. Start the engine to see if it will run.
If your SCAG mower starts and won’t continue to run, you will need to remove your carburetor and take it apart for cleaning. Check out this article for help with disassembling and cleaning the carburetor on your SCAG lawn mower.
Bad Fuel Cap
A SCAG fuel cap is designed to vent. This is to allow air to pass through the cap to equalize the air pressure in the fuel tank.
Without a vent, the fuel tank will form a vacuum keeping fuel from flowing out of the tank. This vent can be plugged causing your mower not to get the fuel it needs to run.
Identify whether your fuel cap is the reason why your mower isn’t getting fuel by removing the cap and allowing it to run. If it starts and runs, replace the cap with your SCAG still running.
Let it continue to run for a while to see if it runs sluggish and dies. If it does and then starts up again after you remove the cap, there’s a good chance the cap is bad.
Solution: Replace your gas cap.
Still Experiencing Problems with Your SCAG Lawn Mower?
Own a lawn mower long enough, you’ll start running into problems with it starting, not continuing to run, smoking, leaking gas, giving a bad cut, vibrating, or another issue.
To help you save time and money, I have put together a guide to help you troubleshoot the next problem that develops on your mower.
You can find this guide at Common SCAG Lawn Mower Problems & Solutions.
If you are unsure how to perform diagnostics and repairs on your lawn mower safely, it’s best to have a professional complete the repairs.
This will help you avoid personal injury or additional damage to the mower. Your local SCAG lawn mower dealership or lawn mower repair shop will be able to help you solve your problem.