1.8T Fuel tank, rails etc - help

[GeraintUK]

Evening Gents,

On my new build we've determined that we should change the fuel rail for an aftermarket one for a few reasons but as I was looking at it all today I reported back to my engine builder that I couldn't find a return.
This sparked off loads of questions and referring to diagrams on rimmers and confused as hell at present.

Am I right in thinking on the ZT that there is only one fuel connection direct to the rail and that the other end is just a valve that has what looks like a tyre valve cover over it ?

How does the fuel purge valve work?

Basically on a TF fuel rail it has a fuel in and fuel return which is exactly all we need, but not sure what's going on with the purge valve as when I looked under the car there are two pipes from rear and one goes to rail, the other to the purge valve. Is there a proper "return" line on the tank.
Also, does anyone know if the pipes are all rubber or if there is any metal pipes or connections as the plan was to replace with Aeroquippe hose.

To sum up, the ZT fuel system has me baffled.

Any pointers would be greatly appreciated.

Cheers
Geraint

[T-Cut]

Am I right in thinking on the ZT that there is only one fuel connection direct to the rail and that the other end is just a valve that has what looks like a tyre valve cover over it?

Yes, that's correct. Under the blue cap is indeed a Schrader like valve. Perhaps one resistant to petrol, I don't know. The purpose of this is to allow rail depressurisation if required and a means of measuring the delivery pressure (around 50psi).

How does the fuel purge valve work?Surprisingly, it's never been discussed to my knowledge. My understanding is that the petrol vapour absorbed in the carbon canister under the rear end is evacuated off by the depression in the inlet manifold. The ECU decides when the conditions are right for it to open the purge valve which is below normal running temperature. The valve seems to be operated in pulses related to engine speed. My impression is the car is stationary as well. The purging seems to stop when moving off. There's a sort of write up about it in RAVE if you have that.

I don't think there is a fuel return line in petrol engines. The diesel has one because of the delivery pressure necessary and that this needs a positive displacement pump. Petrol pumps are all centifugal so will run against a closed outlet without issue.

I believe fuel lines are made from a plastic of some sort.

TC

[GeraintUK]

thanks for that TC A strange setup indeed.

Now what's going to be cheaper, modifying the ZT fuel tank or an alloy aftermarket one, hmmmmmmm