The Non-Return valve in fuel line

[perrya]

where is the non-return valve on the fuel line. This valve stops fuel from draining back into the gas tank when the car is off leaving fuel in the line for starting. if your car lacks fuel after sitting long periods of time, this could be it and in my case, likely is. This valve must be leaking fuel back into the tank when the car sits overnight so when I try to start, it is difficult (however, once started, it runs fine all day and starts up immediately).

But, where is it located? right before the fuel pump? After? what does it look like? this seems to be a mechanical device so it will not throw a code if it fails.

 

[Seatman]

There isn't one, fuel leaks back to the tank because air is getting in somewhere breaking the vacuum seal so to speak and allowing a syphoning of the fuel from the lines and filter.

 

[rotarykid]

on the early A4 body cars there was a return valve in the fuel line at the tank, I have replaced this before on several cars that were loosing prime....

 

[perrya]

According to a 2006 VW training guide for my car about the fuel system, the non-return valve is between the fuel filter from the tank and the fuel pump. It seems to be a mechanical spring of some sort. Assuming there is not one, how does one trace or find where the fuel pressure leak is in the line?

 

[wonneber]

According to a 2006 VW training guide for my car about the fuel system, the non-return valve is between the fuel filter from the tank and the fuel pump. It seems to be a mechanical spring of some sort. Assuming there is not one, how does one trace or find where the fuel pressure leak is in the line?

I'm wondering if you are talking about the thermal 'T' valve in the fuel filter in the engine compartment.

 

[BobnOH]

Related thread

 

[Seatman]

I drilled out the sender in mine, never lost prime, only lose prime if air is getting in allowing the fuel to run back.