I tried searching and looking at the diagrams, but no clear answer, looking at the back of the tank the bottom fuel connection is that for the fuel return, and the top is for? Venting I'm guessing, I want to put a fuel filter on the return line, thanks

 

The return line starts at the pressure regulator, goes across the front of the cylinder head (right below the breather), then goes to the fuel cooler. Existing the cooler, the line goes (approx) below the left floor board on to the rear of the car. It branches out in two directions to the right and left return valves and then from each return valve to the respective tank.

The return fuel enters the tanks at the top....memory a bit foggy on the *exact* location but if you run the engine you can see return fuel flowing into the tank if you open the filler cap.

There's a tiny hole in the filler neck. That's a vent hole, not a fuel return.

I'm a bit curious as to why you'd install a filter on the return line but, anyhow, it would probably be easier to do so in the engine bay on the line that exits the fuel cooler

Cheers
DD

 

^ The above assumes a Ser III XJ6 4.2 ^


Cheers
DD

 

Sorry should of included that, it's a series 2, the tanks were rusted got them all cleaned up and sealed, there is a possibility that there is rust, gunk, varnish still in the line and want to prevent it from flowing back into the redone tanks, so I was thinking a filter right before the tank would be the safest bet, on the series 2 tank there is the feed to the fuel pump on the bottom, and two lines on the back, one in the trunk, and one outside side, is it different on a series 2, thanks again

 

I too would like to know where the return line is. is it the line behind the carpeted board on the side of the inside of trunk? im bypassing both tanks and having everything go to my 15 ga. fuel cell. rust killed both tanks and numerous fuel pumps

 

Is there an easy way to bypass the return diverting valves? my RHS tank is rusted beyond repair, and a temp fix for my parts car to make it a runner is to just utilise the LHS tank and feed/return lines.


Where exactly are the return valves? inner rear wheel arch?

 

Here is an internal view of the tank... This is a series 3 tank, and there are some variations... but for the most part, the fuel returns in the same way..
It comes down the LHS of the car via a hard line, T's at the rear (going along the arch for the IRS), and then returns through whichever solenoid is open, through the bottom of the tank and up a line inside the tank to dispense at the filler cap...

For a return filter, the only logic place would be at the rear of the fuel cooler (in the engine bay near the A/C compressor)... Otherwise it's hard line from there...

There are some variations, especially with the Series 2 XJ12...
but as far as most of the XJ6, this will serve a good illustration...

Cheers
David
Everyday XJ

 

Stoney85....

If you are going to utilize only the LHS, in theory you should be able to leave things just as they are. The system is designed to default to the LHS...
However, if you wanted to be extra sure, you'd simply remove the valves (yep, in the fender arches), and install a connector on the left side to let fuel pass all of the time... On the RHS you'd install a plug ... And in the trunk you'd just do away with the change over valve, and connect the fuel pump directly to the LHS tank. Then the RHS tank would be completely isolated.
I ran my 84 like that for years...
However, just remember that the connector that you add, as well as the plug, have to be secured very well against leaks... Anything that drips from there goes straight to the exhaust below...

Cheers
David
Everyday XJ

 

If you guys want to see the return lines at the rear, in the IRS tunnel...
Here, in the 2nd column, 4th photo down.. All of the lines, and the T that takes it to both sides...

(To answer the question above... None of that is behind the carpet in the boot, it's all under the car... )

Anatomy of a Series 3 XJ

David

 

wow David, that is real anatomy if I ever saw it. Thank you for the Service to all of us.

 

David, thank you!


I've already isolated the new fuel pump to only be fed from the LHS tank, old one was seized due to rust from RHS.


I wasn't sure about the fuel return setup and its operation, again, thanks for the information, I feel I will bypass the return valve and replace with a connector to join the return line to the lhs tank, more so for complete peace of mind.