Look on your lawn mower’s gas cap for a small vent. Keep an ear on your fuel tank and listen for any strange sounds when your lawn mower stalls. So you might come across a bubbling sound coming from your lawn mower tank as these gases move through the fuel lines. Once the gasoline turns to vapor in the fuel system, the gases will work their way back toward the gas tank. If the engine stops when the intake and exhaust valves are both closed, then there is no way for the fuel vapors to escape. This is because there could be too much pressure inside the cylinder head. When the lawn mower engine stalls because of vapor lock, you might find it hard or impossible to pull the starter cord and turn over the engine. Potentially, you’re dealing with a vapor lock in the fuel system. So, if your mower has plenty of gas, a good spark, and oil in the engine, then something else is going on. This is because the fuel vapors are still inside your lawn mower fuel system. Often when your lawn mower has stalled because of vapor lock, it can be very difficult to get your lawn mower engine restarted. The problem is not because of a lack of fuel in the fuel system but the lack of fuel flow. Another sign of vapor lock is that your engine sputters and stalls even though you have plenty of fuel in the gas tank. So, if your lawn mower is stalling for no apparent reason, then vapor locking could be the issue. When the vapor lock or blockage is too great for new fuel to pass, the engine stalls. The next stage after sputtering is engine stalling. So, if your lawn mower sounds like it is running out of fuel, then it could actually be a symptom of vapor lock. As this happens, the engine will gradually receive less and less fuel, causing the engine to sputter. As the fuel begins to heat, it creates small bubbles in the fuel system that slowly start to affect the lawn mower’s engine. Vapor lock on a lawn mower is a gradual process that slowly worsens as the gas builds up. Here are some telltale small engine vapor lock symptoms you can use when diagnosing your lawn mower. So, how can you determine if vapor lock is the cause of your lawn mower problems? Well, there are several vapor lock symptoms you can watch out for. Vapor Lock Symptoms (How to Tell If Your Mower is Affected) This back pressure prevents liquid gasoline from traveling through the fuel system, and the lawn mower’s engine becomes starved of fuel. The gas creates back pressure in the fuel system, causing a blockage. Vapor lock happens when gasoline in the lawn mower’s fuel system reaches a certain temperature and turns from liquid into gas before reaching the carburetor. 3.7 Keep Your Lawn Mower Clean What is Vapor Lock on a Lawn Mower? (The Short Explanation)

Gas vapor lock