Is there a o ring at the low pressure fuel line rail?

There's not a single, universally applicable answer to whether there's an O-ring at the low-pressure fuel line rail. The presence and location of O-rings vary significantly depending on the make, model, and year of the vehicle, and even the specific fuel system design within a model year.

Some fuel rail designs use O-rings to seal the fuel line connections to the rail, others may use different types of seals, such as crush washers or even specialized connectors without O-rings.

To know for sure if your specific vehicle has an O-ring at the low-pressure fuel line rail, you need to:

1. Consult your vehicle's repair manual: This is the most reliable source of information.

2. Check online parts diagrams: Many auto parts websites have diagrams that show the fuel rail components and their seals. You'll need to enter your vehicle's year, make, and model.

3. Visually inspect the fuel rail: If you're comfortable working on your vehicle, carefully examine the fuel line connections to the rail. You may be able to see the type of seal used. Caution: Always disconnect the battery's negative terminal before working on any fuel system component.

Without knowing the specific vehicle, it's impossible to give a definitive answer.