What are the symptoms of a vapor lock?
Vapor lock causes:
Table of Contents
- Loss of fuel pressure (and flow)
- Loss of power.
- Stalling.
- Difficulty restarting the engine.
How do you fix vapor lock?

Once the fuel system has cooled, you can help eliminate any vapor left in the fuel system by first pressing the accelerator pedal slightly (do not press it to the floor) while cranking the engine. Once the engine starts, hold the accelerator pedal down until the vehicle runs smoothly, indicating the vapor lock is gone.
How do I stop my engine from vapor locking?
If you’re wondering how to prevent vapor lock, try using a thermal barrier like a heat shield, or heat sleeve. Whether you have a carburetor or use fuel-injection in your vehicle, vapor lock can bring your vehicle to a standstill causing hours of frustration.
What happens when a car gets vapor lock?
Vapor lock happens when your fuel boils in your carburetor or your fuel line. Vaporized fuel creates back pressure in your fuel system and prevents gas from getting to your engine. It commonly occurs when a car has been idling or has been turned off and then back on.

Does higher octane gas prevent vapor lock?
High octane gas is both unnecessary and can increase the likelihood of vapor lock by introducing higher levels of ethanol when used as the octane booster.
Can vapor lock occur while driving?
If the outside temperature are high or the engine is running at higher temperatures and the fuel lines are routed too close to the exhaust, a vapor lock can occur. It can also happen when driving at higher altitudes or if you run a winter fuel blend in your vehicle once the weather gets warm.
Can a dirty fuel filter cause vapor lock?
Several Factors Can Contribute to Vapor Lock:
Fuel lines next to or touching hot engine components. Lose of fuel delivery system pressure or flow (volume); this may be caused by a restricted fuel filter or insufficient voltage to the fuel pump. Fuel pump next to hot operating engine.
Can fuel injected cars get vapor lock?
Vapor lock is usually caused by overheating, so the solution is to lower the temperature of the fuel system**. Most modern cars are fuel-injected.
Will a carb spacer help with vapor lock?
Trans Dapt’s insulated carburetor spacers are developed to provide excellent protection from heat soak and power loss caused by vapor lock and percolation.
At what temp does fuel vapor lock?
Vapor Lock: Watch Fuel Boil and Learn Tips on How to Avoid It
How long do you have to wait for vapor lock?
As you shut down, the heat rises up toward the fuel lines. Without air moving through the cowling, fuel in the lines can start to vaporize. Generally, if you experience vapor lock, it’s when you try to start your plane after a quick turn (shut down and restart within ~30 minutes).
Will an electric fuel pump cure vapor lock?
An electric fuel pump can eliminate a vapor lock when properly installed and I stress when properly installed. They should be installed as close to the fuel tank as possible. They should never be installed in the engine compartment for two reasons, distance from the tank and excessive heat from the engine.
What does a 1 inch carb spacer do?
A carb spacer gives your manifold a longer neck. And this increases the volume of your intake’s plenum and runner, as well as the total distance between the bottom of the manifold and the bottom of the carburetor. These increases create the space needed for the intake mixture to straighten out.
What causes a engine to vapor lock?
High underhood temperatures. Fuel lines next to or touching hot engine components. Lose of fuel delivery system pressure or flow (volume); this may be caused by a restricted fuel filter or insufficient voltage to the fuel pump. Fuel pump next to hot operating engine.
At what temperature does vapor lock occur?
When modern injection motors are stopped after long travelling, some might not be able to restart immediately. The reason is that those new motors reach temperatures up to 120-140°C, and vapor lock is prone to happen at high temperatures. Especially with modern fuel blends vapor lock issues show more frequently.
How much horsepower does a carb spacer add?
On the 350, best results were found with a 2-inch spacer. Its use produced up to 6 more horsepower at peak and as much as 14 more at 750 rpm over peak power. On the 400-inch engine, a stack of three 1-inch spacers produced the best results.
How common is vapor lock?
Fuel-injected engines use a more volatile fuel that is easier to vaporize and mix with air for a much better combustion. So this new fuel has a lower boiling point. However, vapor lock rarely occurs in a modern engine because of the use of an in-tank, electric fuel pump.
Can a fuel pump cause vapor lock?
Still, a modern fuel-injected system can suffer from vapor lock, not only if pressure in the fuel line drops (faulty fuel pressure regulator or fuel pump, for example) and the fuel line is subjected to high temperatures, but also modern engines that may reach between 248 and 284 F (120 and 140 C) using ethanol blended …
Are 2 inch carb spacers better than 1 inch?
“The further the carburetor boosters are from the intake valve, the more that air/fuel droplet has time to vaporize; the more time the air has to get chilled.” Two-inch-tall spacers are generally a good baseline height choice on race cars; for street cars that operate at lower rpm and usually have hood clearance …