Fuel Line diagram

Is there such a thing as front to back diagram for the Series lll showing all the parts and their connections ?

https://parts.jaguarlandroverclassic.com/parts/index/hierarchy/id/C06.C0619/brand/jaguar/

Derek,
Three good sources for that information are the Jaguar Series III Service Manual, the Jaguar Series III XJ6 Parts Catalogue, and the Jaguar Series III XJ6 S57 Electrical Guide. I purchased the hard copies that I own on eBay and have used them regularly during my past 20 years of Series III XJ6 ownership.

Paul

Thanks Paul I’ve just checked it out.
Cheers, Derek

86 XJ6 series III
Moving on …

  1. Is there a process for pressurizing the fuel tanks and lines to detect
    leaks ?
  2. has anyone ever installed a new fuel line route from pumps forward to engine (abandoning existing) and is this modification legal ?

Derek,

fuel tanks are pressure tested by the people working on them before returning them to the customer. You’d have to pull them though. I never heard of anyone testing tanks in situ … which in itself doesn’t mean a lot, I admit.

As a rule you check for leaks by just cleaning them and putting talcum powder over them. Then fill up the tank. Even pinhole leaks allowing fuel to evaporate as soon as it comes out will mark the powder.

If you distrust the fuel lines, replace them. Why on earth would you want to put them anywhere else? Their routing isn’t that bad.

Good luck

Jochen

75 XJ6L 4.2 auto (UK spec)

1 Like

I agree the routing is fairly good but early in my ownership I got caught out by the steel pipes (flow and return on the V12) that pass from the tank unions through the space occupied by the rear mufflers into the spare wheel well and the pumps. This area tends to get filled up with mud and grip and the pipes can pinhole easily in this mixture leading to a very smelly cat!

Best regards,
Mike (1973 DDS S1)

1 Like

Thanks for replies.
Obviously I can smell gas (and not during a fill up). Is there a way to test where a leak is occurring - tank to engine without pulling the car apart ?
I’m thinking a dye under pressure, segment by segment.
Other tried ideas ?

Right, Mike,

in fact I had the same problem: metal fuel line “rubbed” through where it comes from the exhaust box into the trunk. Good rubber grommets are highly recommendable! But that is not the line from the pumps to the front Derek asked about. So I’d still stick with the original routing.

Have a great week end

Jochen

75 XJ6L 4.2 auto (UK spec)

Derek,

even though it may be little consolation, rest assured that you’re not the only Jaguar series driver suffering from this problem. Most of us have been through it, are in it, or may just have adapted their olfactorial senses to live with it.

Maybe, you first try to narrow down your issues: first of all, do you smell fuel fumes or raw fuel? Both get hard to distinguish once an engine runs overly rich. Then spend time with your car, sit inside, walk around, open the hood, open the trunk - when and where is the smell stronger, not so strong? Does it concentrate in the trunk or around the engine bay?

Chances are you either have a leak in the engine bay around the injection or between the tanks and the fuel pumps. Without even looking at the car I’d acquit the metal fuel line between the spare wheel compartment and the right front wing mounting where the rubber fuel line starts. There is no reason for a fuel line to break in this area - except maybe you have excessive rust.

Check out the rubber lines in the engine compartment. Everything dry? Have someone cold start the car while you look at the connections. Often leaks occur during phases when plenty of fuel is moved around and with minor leaks fuel may evaporate before you get out of the car and to the engine bay or the trunk.

Next do the same thing with the rubber hoses in the trunk. I found my four banjo bolts on two fuel pumps a pain in the neck to get dry. With the valve and the fuel filter there is a lot of plumbery with high chances something is amiss. By the way, open fuel won’t just smell, but it stinks incredibly. “Simple” raw fuel smells are caused by joints that are anything less than bone dry. Just a little dampness - which won’t be cured by being wiped off - may cause your problems. As Mike’s posting and my last reply indicated, don’t forget the fuel line leading from the wing through the exhaust box and through the side of the trunk compartment. There is a lot of movement there that may have done damage even to the metal fuel line.

Now, unfortunately, this is all you can do without serious work (removal of rear bumper, rear quarter panels, tanks …). However, chances are you find the culprit before.

If not, you can try to narrow down the issue by running one tank empty and only run on the other one. If the problem remains, it might be the tank in operation. Cross-check on the other tank.

Very tedious and bothersome, I know, but, frankly, every couple of years I’m doing the same thing. Once I found a leaking fuel pump, once I found a leaking banjo bolt, once I found a pinhole in the metal pipe … Don’t ask me why no Toyota or Ford ever gives such problems.

Good luck

Jochen

75 XJ6L 4.2 auto (UK spec)

Gentlemen thank you for input. Unfortunately it’s the ‘very tedious and bothersome’ aspect of the problem that I’m trying to avoid. Reason for this is I can’t take care of the problem myself and I figure it’s going to break the bank to have a mechanic investigate :confounded: !

**
It cannot be avoided, Derec - either you or somebody else must do it…

The real quandary is to assess whether you have a problem or not - some petrol smell is unavoidable, and may be innocent. Ie, ‘European’ vent tanks to open air - and even the closed tank ventilation system may leak fuel vapour, as may unsealing tank lids. Neither represent any particular danger.

You can remove the air filter and prop open the filler lids, and the pump will run with the ign ‘on’. This pressurizes at least part of the fuel system without interference from the engine - to be inspected at some leisure, including with the boot floor removed. Obviously, having the car on a lift makes all checking easier - and sniffing around may reveal something suspicious. Or, over time, get some clues as to when and where you smell something

But, as Jochen says; there are no easy ways - and the most difficult is to decide if you have a problem…

Frank
xj6 85 Sov Europe (UK/NZ)
**

Quoting this for emphasis !

Often people smell gasoline and are perplexed because they don’t find an actual, drippy leak.

Just a tiny ooooze will give a easily detectable odor, especially in a confined area. A wet, drippy leak will be almost overpowering.

The odor can permeate thru rubber hoses as well.

FWIW I eliminated 90% of the fuel odor in my boot simply by using marine grade fuel hose. It’s ultra-low permeation. I can look up the exact spec if anyone is interested

Cheers
DD

Derek,

with all due respect, but where is your problem? The procedure I described will cost you just a bit time + you need a Philips or Pozi screwdriver to get access to the compartment underneath the trunk where the pump and the plumbery live in. Checking all joints at the pump, the valve and the filter is dead easy. For changing fuel hoses you order the correct hoses and maybe seals for the pump. In the worst case you’ll need a new pump or valve, everything available and not very costly. In tools you only need a wrench for the banjo bolts at the pump. So far every bit of work is purely Saturday afternoon shade tree work - the hard bit where you might think of farming out and letting the experts do the job indeed is the tanks. - Many series Jags were grounded due to tank issues.

Go ahead and keep us posted!

Best

Jochen

75 XJ6L 4.2 auto (UK spec)

Thanks again for replies. Bottom line is I’m not able to do the work myself. I’m sure we all look for quick fixes first. The pleasure of owning a fine XJ6 comes at a price, so I’m going to bite the bullet and have a mechanic look at a fix.
Again, is it possible to abandon the existing and run new some where else without pulling the headlining down and all that entails ?

I hate to flog a dead horse as everybody has gone to some length with much appreciated suggestions but I would still like to know if it’s possible to abandon the original line and run all new somewhere else ?

The headlining has nothing to do with the fuel lines.
Yes, you can run new lines, but they have to go under the car, and they have to be metal.

**
What is actually the problem with the original, Derek - from where to where…?

Frank
xj6 85 Sov Europe (UK/NZ)
**

Trying not to spend hours and hours trying to find the leak causing the smell and the associated costs.

Sent from Derek’s iPad

Sorry, Derek, but a seriously routed new fuel line go-and-back (for FI cars) will take hours more than some really, really simple checks: All of the fuel lines from the spare wheel well to the engine and return are plain visible except for the parts from the tanks into the exhaust boxes and through to the spare wheel well. However, it is the latter that will give you pain in the neck no matter whether for checking or for swapping, because there is no other access but to remove the rear bumper and the rear quarter panels.

So, yes, by all means: you are flogging a dead horse. You’ll be a lot better off by simply doing - or having done - a simple job. We still have no indication as to why you suspect a problem in the fuel lines - again: from the spare wheel well to the engine and return - in the first place. 90 :10 your problem is between the tanks and the spare wheel well … and it won’t go away with new fuel lines at other places!

Good luck

Jochen

75 XJ6L 4.2 auto (UK spec)