In the early 1970's I lusted after the XJ6. I thought it was the most beautiful thing on wheels, but I worked in a filling station and these were rich guys' cars. The first time I noticed a customer filling up an XJ6, he seemed to take quite a long time to fill the tank and it came to quite a lot of money for the time but then I saw him go around the back of the car and he opened the other filling cap and started filling it again. This really impressed my teenage brain. Within a year, thanks to good fortune I bought my own. As soon as I could, I took it to a filling station and told the attendant to "fill her up - both sides". I loved that car.

One point about the system , on S3s at least, is that the fuel selection for the right tank requires the valve to be powered (ie working, no wiring faults or blown fuses. When the system is passive , fuel is drawn from the left tank. When I do long trips I draw down the right tank first (use it while you have access), then use the left. It can be a long way between gas stations where I live.

I was a bit baffled on my series 3 V12 as the fuel always returns to the right tank- now I know why. I did modify mine so that I have two pumps instead of just the one as my changeover valve had died and a new pump was cheaper!!! Now the relevant pump is selected and then ( of course ) the left pump was filling the right tank from the return. A big thank you for explaining all that. I shall delve into it in the next day or two.

Great content. Just getting back into my old 1987 VDP V12.

Hi Adam,..thanks for sharing and explaining how the twin fuel tanks work. About a month ago I bought a 1982 Jaguar XJ6 Series 3 and now I have a good idea on how those twin fuel tanks work. Thanks Adam. A hello from Boston, Massachusetts, U.S.A.

Love your videos, thanks for posting. There isn't much content online for old Jaguars, particularly V12's.

@LivingWithAClassic

4 жыл бұрын

Glad you enjoyed it! More V12 content coming soon 😊

Great video !! I have a S2 xj12l. And have no valves at all. Just drawing on left only. I’ll be putting it straight this summer !! Thanks !!!

Very interesting I just bought an S3 XJ6 and I am thinking of making a compartment for the pumps and valves to separate them from the trunk so your luggage has less interference with this and less chance it start to smell of fuel if a leak occurs

Great info once again 👍

@LivingWithAClassic

4 жыл бұрын

Thank you!

Just bought one with a 350 chevrolet conversion. Thanks for the explanation.

Very useful information!

@LivingWithAClassic

4 жыл бұрын

Thank you for watching!

I just resubscribed and this is just the information I need to fix my 1978 XJ6L fuel switching issue! Overfilling the right tank when running

@LivingWithAClassic

Жыл бұрын

I’m glad I could help

I love the way these jags were designed

I have a Series 3 XJ6 that's not returning to the right hand tank but at least I now know where to look. Thank you

Useful video

very good explanation thanks.

@LivingWithAClassic

Жыл бұрын

I’m glad you liked it!

Thank you 🇺🇸

My father converted our 1979 series 2 xj6 to 1 pump system and the valve system was control by the dash switch he kept having issues with the two pump system so in 1981 he looked at his series 3 fuel injected system and made something similar for carb fed engine . Father is a great engineer he so skilled. Because he can draw up systems and make them where i can do the theory but not so good and the practical Other than rover and lancia jaguar xj6 are my fav cars. My dream is to convert one to an ev . But being colour blinds wires are an issue

Many thanks, exactly the info I was looking for! (I have a 1982 Daimler Sovereign (XJ6) with a leak from the right tank :-) )

@LivingWithAClassic

Жыл бұрын

I hope you find the leak

Amazing that you have any fuel return on the v12. 😂😅

Two tanks,great! Put diesel in my XJC by mistake in Hamburg.No problem,put petrol in the other tank and drained the diesel next day through the plug at the bottom of tank.

One of the things that has always interested me is crash safety and how it evolved. I usually drive American cars and I like 69-72 the best because they had the small bumpers, but also a modicum of safety equipment. I'm really surprised to see how the fuel tanks are setup on these jaguars! Especially since we had a big thing here on the states about chevy trucks from 73-87 having fuel tanks outside the frame rails that would rupture and catch fire in a side collision. Also 65-70 or so mustangs have a drop in fuel tank with no firewall on the rear seat so a rear end collision could rupture the tank, and slosh fuel into the entire interior of the car if the rear seat came loose in the collision. I'm surprised I never heard anything about how these Jaguars do in a rear end collision. The location is very vulnerable to an offset rear collsions and the pumps and electronics near the rear are ripe for a spark. I assume the relatively low production of these compared to my other two examples is why i have never heard of them. I can't even google a picture of a crashed xj6. Sounds like a fuel cell or foam racing style tank would be much safer. I had assumed the duel tanks were under the rear seat like more modern cars and they needed the dual tanks because the driveshaft was in the way.

Brilliant! Question : On my 1981 XJ12 H.E. there is no swoosh sound when I open the filler caps, indicating there is no underpressure in the tanks. However, on my 1985 XJ-SC 3.6 TWR (with one tank only) there is a definite swoosh/underpressure sound. Can it be clogged ventilation or something else? Incidentally, my 1988 V12 Sovereign also had the swoosh sound. Aside from using air pressure etc to blow out ventilation pipes, is there an easy-fix in the filler cap area ?

I found out this to my cost when fuel started pouring out all over the road. haha!

@LivingWithAClassic

4 жыл бұрын

Many XJ owners have found our that way. Hope the car was ok!

Thanks Adam.Greetings from Cape Town,S,Africa.Just discovered your channel and subscribed.Had a general idea how the twin tanks worked,but you filled in the blanks.Starting to restore fuel system of a '89 Double Six I bought recently which had been standing for years at the previous 2ownwers.Managed to drive it home 30km running on five cylinders.Got the Haynes &factory workshop manuals & even 1 showing how to install a Chevy V8,which is also quite popular here,but looking forward to viewing all your videos on especially on the V12's.Also have a properly runing '84 XJS-Cabrio 5.3HE and need all the tips and help I can get to keep them running.You have any experience on converting a V12 to a manual transmission?

twin fuel tanks in Jags started with the MK-X, then the S type then the 420, then the 420-G, then the Series 1, 2, and 3 XJ-6 and XJ-12 from 1968 to 1992.

@frankkemble2103

Жыл бұрын

Yup!

@thomasgolodik3734

8 ай бұрын

Actually, started with the big sedans in the 1950s-MK 7, 8 and 9. Two tanks, two pumps.

I have a series 1, and have a question regarding the upper tank hoses on each side. On the top of the tanks closest to the back of the boot, there is a metal outlet valve coming out of the circular hole in the body with a hose attached on each side. Mine are not connected to anything. When i fill up the tanks, the fuel smell is extremely strong. The question is what are those hoses supposed to be attached to and is that where the fuel smell emanates from?

Thanks great video . I like to be ready for the gremlins 😊

Yes Series 3 , valves under rear wheel arches, one rattles one doesn't.

Does anyone have info over the "In Tank" pump versions or where they were available? Im removing the tanks today and the fuel system looks a little different than each of these??

It is obvious that it is critical to know how to tell if fuel is returning to the correct tank. I drove xj series 2 o a warm day. When I shut the engine off I smelled fuel at rear of the car. I opened the tank.door and high pressure vapor rushed out, taking over a minute Thor the pressure to normalize with atmospheric pressure. ( also my ac was not working.)

I need to know if there's a third fuel pump on a 95 Jaguar xj12 I got the back too in the tank running but for some reason I'm sure not getting no fuel to the engine

I am in the process of designing a dual tank fuel system for my Aston Martin DB5 replica project. I am using a 1966 Jaguar XK 4.2 engine from a 420. I am using a 1996 BMW Z3 unibody "chassis" for the suspension, steering, brakes and main structural substructure....wheelbase and trackwidth are fairly close. Since the XK engine is very heavy I think it is important to shift as much mass as possible to the rear to help balance the car for decent handling. Therefore rear "saddle" tanks behind the rear wheel wells very similar to the Jaguars make sense. Non A/C DB5s also used dual tanks for that reason. The Lotus Esprit also had dual tanks, but with a "balance tube" so that fuel could be filled from both sides ...as well as being burned equally. Is it possible to use a balance tube in a Jaguar fuel system, and have one pump and filter? Thank you.

I have an 82 xj6 and it has a strong smell of fuel in the interior more so when stationary and not running. Any idea what that may be?

hi buddy i have a xj12L 1975 had all new fuel lines new pumps carbs rebuilt i ran the car but stored it over winter i put gas additive in both tanks now i turn ovwr the new pumps working but no fuel to the carbs car wont start even the tanks each have $50 in each but my emergency cut off valve under dash at passenger side wires are of is this the problem please and thanks super videos by the way keep up the good work

It seems that the reason why there are twin fuel tanks is that the big spare wheel did not fit in the beautifully sloping boot, otherwise than laying horizontally on the boot bottom. The spare wheel thus took the place of one single tank. Then two smaller tanks were fitted in each wing to give the car sufficient range. I suppose it was a technical complication to have the twin tanks filled via only one filler cap.

@frankkemble2103

Жыл бұрын

The twin fuel tanks was a feature on many of the Jags- not just the XJ and the reason given was to liberate space and help the balance of the car.

HAD A FEW 84 -87 XJ6. VDP ,FEW TIMES PUT SMALL T PIPE TO MERGE THE TWO TANKS ,UNDER SPARE TIRE IN TRUNK..FOUND IT EASYIER THEN FIXING FAULTY GAUGE

@SubParGolfers

5 күн бұрын

Do you have a link for the small t pipe?

You mentioned you replaced the OE pump on your series two with a later Bosch from the HE system. Would you happen to have that Bosh part number? I think I found it as Bosch 69469, is that correct? I'm fixing a 76 Series II that was sitting at my local airport since 94. Only has 15k miles!

Hey! So I’m having issues with my series 3, every time I start it fuel spews out of the right fuel tank, I heard you can install a Tee tank kit but do you know what could be causing this? And what I should do to fix this? You’re my only hope!

Did you cut some openings for service access to rear brakes? Looks like ut @12:30min

Hi Adam I am attempting to return a 1978 Series 2 XJ6 barn find back to a daily driver. I have an issue with the tanks as the left just feeds the right. Sometimes it runs ok but eventually it runs dry by pumping into the right tank. I have a South African S2 which has intank pumps but with carbs. I do not see any valves in system nor an I see a return line. It appears to be one line from the right hand tank with a “Tee” accommodating the left hand tank fuel line. I know that these South African as well as New Zealand and Australia were basically left over parts models but I basically can only use one tank on this set up. I don’t think the Vehicle has been modified so any suggestions.

Hi Adam Like you channel have you got your air intake for the heater (by the wipers) on backwards ? on you series 2 v12 ! As it is the opposite for British Jaguars

Hi adam Great explanation I own a series 2 6L The precious owner replaced the 2 fuel pumps for one electric pump When i started the car after the wintertime (4 months in the garage), no fuel was coming from one of the tanks. After checking the pump, I could not find anything After switching over manually to the other tank, fuel starting flowing and the car started without any issue Hearing to your explanation, could it be the valve is stuck? I deliberately moved over to using ecofriendly fuel (aspen based) before the wintertime in order to prevent these issues What is your guess the problem could be? PS both tanks were fullwhen parked for the winter

Hi Adam. I'm Neil in UK, and thinking of buying a nice condition XJ6 1986 4.2litre Jaguar. So I know it has two fuel tanks, but how can I check to see if the tanks are in good condition before I purchase the car, as I understand they can get quite rusty under those rear wings. The car has been stood for a few years, but runs. But it wont run smoothly, and cuts out when releasing the throttle. Seems to be running on all 6 cylinders ok. Any advice you could give me will be much appreciated. Thanks.....Neil

The Series 3 I bought yesterday has right tank disconnected, the return switch has been removed, I'm guessing it failed & one tank was overflowing. I will investigate & get both tanks working, however, the car has barely been driven for years, other servicing, maintenance & cosmetics will take priority in coming weeks, it will be some time before both tanks are operating.

@ricardyjeanlouis7888

2 жыл бұрын

How did you go about the failed tank? a year later*

can u help please mine is 1988 and is with locks oh i can open

Does the XJ12 require premium or regular gas?

Great explanation, thanks! Recently purchased XJ6L. Note, it has a GM 350 conversion. I have never pushed the dash "Fuel" switch. At fuel stops I fill BOTH sides and they always have taken equal amounts to fill up. Was something changed in trunk? Am I missing something in explanation?

@LivingWithAClassic

Жыл бұрын

My guess is that someone has connected them together in the past on your car. Go check the boot floor in the back and see what it looks like.

Thank you, dear, for your good explanation .. I have Jaguar XJ-12 1979 neighborhood car I just bought .. There is a problem with it, which is that the right-hand tank is overflowing with petrol .. Is there any advice that you would give me to address this problem?

@ohdh8457

3 жыл бұрын

Check the fuel return valves, specially the one for the left side.

Hi, this is very interesting thank you. I was wondering what fuel you use in your 75 series 2? Do you use unleaded and add the special additive? Your advice would be much appreciated as I’m getting conflicting advice regarding my 74 series 2 XJ6. Thanks in advance

@LivingWithAClassic

4 жыл бұрын

I run it on premium (98 octane here). All Jaguars after about 1967 run on unleaded fuel. Thanks for watching 😊

@bobstride6838

4 жыл бұрын

Living With A Classic thank you so much, I did not realise that. I have just purchased my vehicle and I’ve so much to learn! I am very used to old British cars of the era but not of a Jaguar as they were way out of my reach at the time.

Good video but not quite right re all series 3 xj6 have the fuel filter in the boot. I have an early series 3 and the filter is in the engine bay. Also the changeover switch says "fuel" not a picture of a pump as with later 3's.

Bottom end 4.2 litre short block assembly. Creating a dolly to transport my JAGUAR engine. More

Hello super nice videos. Has is xj6 from 1984. It starts to go bad when it's driven about 30 minutes, like it's running gas. Stutters and sets off. If I leave it for an hour, it can go again. There are new filters on it. Do you have any idea? Well, you can help me Vh Jesper lynge.

@ohdh8457

3 жыл бұрын

Did you check the fuel intake valves, because this happens sometimes when the engine gets flooded

Where is the fuel level on the passenger side rear tank on a 75

Does ser 2 xj6 carburetted version have return line? As always very informative. How do you know jags so well?

@LivingWithAClassic

4 жыл бұрын

The XJ6 only has return lines of its fuel injected. I've owned several and done all the work on them myself and also worked on other people's cars. It's become an obsession

@jessekrisher7580

3 жыл бұрын

74 xj12 that is carburated has a return line

Thanks for another great and informative video, I’m watching it now as I suspect that the DD6 I just bought needs a new pump! Hower, you mention the two types of fuel caps, the flush to the body one and the one that’s raised up. Do you know why they were different? On the S3s I’ve had: 1981 German spec - flush 1989 German spec - flush 1990 German spec - raised 1991 Japanese spec - flush I’m happy that the one I just purchased has a flush one, as the one I had before, it really bothered me to have it raised.

@frankkemble2103

Жыл бұрын

Because the flush fit ones were more inclined to let water in if the drain was plugged I think. I know my old series 2 did let water in but the series 3 seems a lot better.

I need the full wiring harness diagram scheme. Where I can get?

@yarpos

5 ай бұрын

for what car? the S1, 2, 3 cars are all different. The S57 wiring diagram is available for the S3 on most Jag forums

Love your videos. Im new to these beasts. I have a strong fuel smell its driving me nuts. I have noticed lines from the fuel tanks into a (something) that I assume is venting under the rear window. There also a plate in the rear parcel tray over the top of it. What is it?

Hi, what are the specification if the fuel pump for a series III V12? Is pressure 3 or 4 bars? Thanks

@LivingWithAClassic

2 жыл бұрын

If you mean a series 3 XJ12 it's about 10 bar from the pump and then the pressure regular brings it down to around 3

@reyrob

2 жыл бұрын

@@LivingWithAClassic I’m fitting a new pump, filter, hoses today and going to try to crank up for the first time! Anything else I should be doing before I try to turn on the engine?

@LivingWithAClassic

2 жыл бұрын

Just prime everything a few times and check for leaks before you try to start it. Best of luck!

I never noticed a switch in the Daimler version. Was it automated?

@LivingWithAClassic

3 жыл бұрын

All the series cars had a switch even Daimlers

Where is the tank switch for a 1972 xj6 series 1?

@LivingWithAClassic

2 жыл бұрын

The switch is on the dash. But if you mean the tank switch in the rear like I showed on the V12, a series 1 doesn’t have one. It is two pumps just like the XJ6 I showed

I wonder how one does clean a tank out

@russellparratt9859

4 жыл бұрын

They each have a screw-in drain plug. At least, the XJ6 does. I assume other similar models do as well.

I really don't see the point of having 2 tanks. Has anybody ever tried to connect both tanks with a hose (bottom to bottom) so it can be used as one big 90L tank?

@specialforces101

3 жыл бұрын

That would make a video worth watching.

@yarpos

5 ай бұрын

yes its been done many times, usually with non return valves so that fuel doesnt siphon between tanks when parked on a slope

Hola , como me comunico con usted, tiene un mails ?? saludos Roman de Argentina

The electrical part of the system was not very clear .

can you take out one tank and drive the car? I have an 87 S3 XJ6.

@djdapper3721

3 жыл бұрын

Yes u can and run of one, not recommend because u would get extremely low fuel mileage

hi, my 1994 jagaur xj6, just purchase multimeter

That flapper will piss you off if you try to pour in gas from a gas can when you can't get to the gas station since the gas will fill up and all over the fender and trunk......I had to pour in a gallon at a time using a large screw driver to push that damn flapper down to hold it and then carefully pour in the gas a gallon at a time.........and when you have an old 1980 you will find that switch to switch the tanks will not have a light that works........THEN you look in the owners manual it says OUT for the right side........well if you have had many different cars in your life you will see people say the right is the passenger side OR the exact opposite by saying it is the opposite when you are under the hood and then the drivers side is the right side......of course they didn't have the stupidass dual tanks either.........now ever try working on the rear disc brakes?.........you won't be happy about that if you do and that is another Jaguar stupidass idea.

@LivingWithAClassic

Жыл бұрын

Or you could just be good at working on them and have it all work as it should. My cars work very well and so do all my customers cars

Jags..... beautiful overall design...... not well executed....

@jessekrisher7580

3 жыл бұрын

you can say that again

@specialforces101

3 жыл бұрын

V12 engine bay looks like an explosion in a parts shop.