My XJ6 has two petrol/gas caps, one for each tank. In the trunk are an assortment of pumps, valves, and hoses that enable the driver to view how much gas is in each tank, select the fuel source, and pump from either side. To fill up, one must visit each gas cap and top up the tanks. There may be a good reason for keeping the two tanks separate, but the only one I can think of is if one side springs a leak it won't affect the other tank.

Why not take out all the fuel switching hardware and replace it with a single hose that connects one tank to the other. The fuel would pass through until the level was equalized. That way, you could fill up the entire fuel system from either gas cap. Also, the fuel gauge would show in total how much gas there was available and eliminate the need to monitor the fuel levels and switch when one got low.

Cheers.

 

That was basically done when my car was converted to Chevy V8. In-tank pumps disabled, but as the tanks themselves are T'd together, the external pump draws from both relatively equally.

Anti-backflow valves prevent fuel flowing from one to the other so it's still necessary to fill both tanks. (I don't have a problem with this as I feel it's one of the charming features of driving a Classic Jag but that might be just me.)

At any rate, the fuel lines are too small for any great equalizing to take place during filling. But if the valves weren't there, they would certainly allow for drainage of the upper tank into the lower one and onto the ground should you park on a side hill (maybe not very many of those in Albuquerque?).

I'm told duel tanks/caps was done for the sake of Styling, as this was the 1970-80s when we shake our heads at a lot of things that seemed like a fashion statement of the time. I rather Like it, but maybe that's just me.
(';')

 

testing my new signature....

 

My old classic cooper s had 2 tanks which were connected together but only the left tank had the level sensor.
You could fill the tanks from either fill point and it would take a few minutes for the tanks to equalise.
The mod could be done to the Jaguar but is it really worth it.

 

My 83 remains as jaguar built it. I like it. If i ver messed with it., I just might add small filters between the tanks and pump. To protect the pum from detritus. Nt a problem as yet, and it has been with me since 2001.

When I visit the gas station, I perform a pirouette to fill each tank and not spill oin te paint!! Just described it on anmother forum, soi, I'll leave it to the imagination here.

A TEE came with my "ump" kit to tie the tanks together. And a warning as to parking side hill with full taniks.. Elinor's one way valves resolve that risk.

 

Fairly common modification. I had mine plumbed that way for awhile. Had no problems.

The only concern is that if the car was parked on a left/right slant the contents from whichever tank was higher would flow into the tank was lower...possibly overflowing it.

Cheers
DD

 

Does one also need to tee the return line, or does the crossover equalize faster than the return threatens to overfill a full tank?

 

Apparently, yes.

I did nothing with the return lines and had no issues

Cheers
DD

 

Sounds like a good idea... we'll see if my incoming has an issue and if so I'll be back bugging all on how to.

As for the two caps....I love pulling in between two rows and filling both at once....draws a lot of looks and comments.

 

Ha Ha! That's a real cool photo!
Only downside is you could be accused of driving a gas guzzler!

 

Uhhh.....

In the US, I think a green boot on the filler nozzle typically means diesel fuel. What's going on there?

 

Looks like German writing on the signs. In Europe, green is generally petrol.

 

Very observant.... I missed that. It looks like the original post is from a member in New York. Unless there is a "NY" in Germany.

 

I think that is in Germany...only picture I could find.


Unless there is a "NY" in Germany.

Well, I'm part German, so there is a German in NY