Hi,
I am currently have issues with my car.

We changed the fuel cap seals as the old ones were worn out, then the next time I went to the petrol station, when I opened the cap it made a woosh kind of noice, I
thought nothing of it and proceeded to put fuel in and closed the cap. I then started the car and pressed the fuel tank button (To change the operating tank, the car has two). After driving for a little bit I started to smell petrol, when I got home I realised petrol was coming out behind the right hand side back wheel.

To fix this problem, we require a diagram of the fuel line in the car to figure out what has gone wrong. I have looked online and found a few although they do not contain the whole fuel line from the back tanks to the front wheel.

If anyone knows what the problem could be or has a diagram it would be greatly appreciated if you left a comment!

 

Welcome to the forums jaglover66, when you gat a moment please post an intro in the new member area.

https://www.jaguarforums.com/forum/n...-intro-must-5/

 

Please DO NOT DOUBLE POST THE SAME QUESTION!!!!!!!!!!!! PICK ONE!!!!!!!!!!!!!

https://www.jaguarforums.com/forum/x...es-3-a-191385/

bob

 

I can't find, online, a single diagram showing the entire system. However the parts catalog might help. Here's one section; from there you can select other sections and get an idea of what the system is comprised of

https://www.jaguarclassicparts.com/u...nd-hoses-trunk

The whoosh and the overflow are probably two different problems.

As for the overflow it sounds like fuel is being returned to the wrong tank.

There are 3 valves in the system: a change-over valve which determines which tank fuel is being drawn FROM and two return valves which direct which tank the fuel is being returned TO. If a valve fails it is possible for fuel to return to the opposite tank than what you've selected, causing that tank to actually overflow.

Attached is some reading on the subject.
Fuel Tank Switchover Checklist, Series III XJ6

The whoosh is likely a problem with the venting system. The venting system can be defective but the problem goes unnoticed if the tanks are not sealed. Replacing the cap seals restored the sealing----which then makes the venting problem apparent. Anyhow.....

The vent system has a couple pressure valves and I can't remember the exact operating parameters to be honest. Most people just unplug the system from the vapor canister, leaving the system permanently vented to atmosphere, and call it good. I can try to find a pic for you if you're interested. Or others chiming in may have a good pic close at hand

Cheers
DD

 

You are probably drawing from one tank and returning to BOTH. The full one overflows!!!!!!
(faulty valves)
Here is some info.

bob

 

Thanks heaps Doug!
Appreciate it

 

Thanks for the quick responses.
Sorry, I probably should have mentioned this at the start.

One tank was just under half full (That's all I refilled it to) and the other one was basically empty.

Wouldn't this make it impossible for it to be an overfilling problem considering there isn't enough fuel to fill one whole tank? Are there any other possible causes for my problem other than overflowing?

@Doug @motorcarman

 

Then I would guess the tank is rusted out and leaking at the rear seam (Like they all do)

bob

 

Thanks for the information.
We are putting it on the hoist early next week and we will know more then. I will be sure to post the updates

Doug, do you also think the tank is rusted out considering it can't be overfilling? It seems a bit of a coincidence that as soon as we fix the seal caps this issue happens.

 

Sure, the tanks can leak via rust holes. Happens all the time.

Cheers
DD

 

Sometimes you can see the seam leak by removing the tail lamp assy.

bob