Hi everyone,

I came into ownership of this car last month after having my daily driver Altima totaled by a careless driver. Sadly, my car troubles seem to be only beginning. I don't know much about automotive work so this probably wasn't the best acquisition in retrospect.

The cab has smelled of gasoline since I purchased it. Not knowing much I assumed it was an exhaust issue. It seems to be a much bigger concern.

The night before what I'll call "the flood" I noticed a drip drop coming out of the driver's side rear end. I put my hand under it and smelled it, sure enough unspent fuel. The leak wasn't that much so I assumed it would be an easy enough fix at a shop.

The leak stopped when the car had been off for a bit.

Then when arriving in the parking lot for my new job, which this caused me to lose, I saw the entire underneath of the car flooded with gas. Gas was pouring out of the driver's side. I drive it home and sure enough after about 30 minutes it stops.

The drivers side take does not work. I'm not sure what's going on, I was simply told it wouldn't be an issue.

I'm assuming this is either a line or a pump or somehow fuel being routed to the second take and then leaking from there.

What's your best guess?

How much is this likely to cost me depending on which problem it may be?

I hoped to get it to a mechanic today but as it's Saturday there's not much I can do. I pretty much want a better idea of things before I take it into a shop come Monday.

 

You could remove the rear under tank cover panels so inspect the tanks, drains plug and lines. The fuel system is very complex on these cars because of the two tanks. It's somewhat common for the return or supply switch over valve to be defective and then the fuel system draws from one tank and returns fuel to the other, eventually overfilling occurs and fuel exists the vent.


If this is not a survivor or somewhat historical car then modify it to use a single tank or if you need the capacity of 2 tanks....bridge the 1/2 inch supply line with a 1/2 inch T fitting for both tanks and fix the return to just one tank.


Also do a search, this subject has been covered here on these forums extensively.

 

Taking on a 30-year old Jaguar XJ6 as a daily driver when you know little of automotive DIY, or indeed the basic technology, can only be described as "Heroic". Unfortunately, unlike the military, no medals are awarded if you manage to get a car running right, only that internal glow of satisfaction of a job well done !

What you have described actually happened to me some years ago with an XJ6 Series 3 and I had the family in the car too ! We will never know why Jaguar used this barmy system of two totally separate tanks, but they did,so we're suck with it. If you're not prepared to fix the system, with its changeover valve and switch, and solenoid operated return valves, you might, as suggested by icsamerica, consider getting rid of the changeover valve, connecting the supply pipes with a T-piece. You then need to remove the return valves, block of the pipe of one of them, and install a straight-through pipe on the other. However, it is relatively simple to troubleshoot the system if you know the layout and the way it works.

 

Before you assume the tank is leaking or one of the fuel valves is bad, do the following check:

1) open the two gas caps and leave them in the open position. No smoking, no lookie-loos.

2) open the trunk, remove the trunk floor carpet, unclip the spare tire compartment panel and remove it from the car.

3) remove the spare tire and any other stuff in the trunk, like the jack bag.

4) use a flashlight to see if there is any liquid gasoline inside the spare tire compartment, it could be something as simple as a loose or cracked hose connected to the Fuel Filter or a fuel line, (the fuel filter is a silver-colored cylinder which will be located on the front and right side of the spare tire compartment).

the above check should take you about 5 minutes.

**the fuel system is under pressure, everytime you are going to replace anything in the fuel system, even a little hose, it should be depressurized.

 

Jose,

Thank you for your trouble shooting advice. I followed your directions, all parts within the trunk are clean and appear to be in good repair. I drove it around for a bit and while it continued to leak from the driver's side there was no gas in the trunk.

I suspect that fuel is somehow being routed to the driver's side tank. When I only drive for a bit the dripping is a problem but not catastrophic. The "flood" occurred after driving around 10 miles. So I suspect that this second tank is filling up and leaking.

Would it be useful to take photos of what I'm dealing with inside of the trunk? There are some tubes and parts nearest the bumper inside the trunk, as well as the fuel filter.

I thank you all for your help and advice. I'm a quick study, I simply need a Rosetta Stone to figure out what is, to me, alien technology.

 

gallowsXJ6, you welcome.

yes, go ahead and check all the fuel lines inside the spare tire compartment, that's also where the fuel pump is, near the rear bumper, but if you say it is dry, then the problem is not there.

Did you smell any strong gasoline fumes when you checked inside the trunk?

next 2 checks:

1) remove the passenger side, carpet-covered panel in the trunk, very easy to remove; Look at the top edges of the panel and you will see some clips under which the panel is held in place. Just pull the panel from the bottom out, and then down. Check around the panel for any screws before pulling and notice how it slides on the right side of the innermost sideways panel.

Behind this panel you will see some line connections at the side of the tank. If dry, replace the panel.

2) remove the passenger side plastic tail lamp lens, (use a medium phillips screwdriver), then remove the 3 large phillips screws in the chromed tail lights housing, for which you will need a larger phillips screwdriver. Pull the tail lamp out complete with bulbs and wiring enough to look behind it;

check with a flashlight at the rear of the tank, you will see some wires connected to a round cover (that is the Fuel Sender Float assembly and connections).

3) run the engine and check again with a flashlight to see if any gasoline is spurting out.

If everything is dry, turn engine off and replace the tail lamp housing then the lens.

 

I have a long distance WAG, The pump is drawing from one tank and returning to the other.


1. Open caps. run engine. Select a tank. Observe that cavity for returning fuel. If you see it coming in, great. If not, oh, oh. Select the other tank, repeat observation.


They oughta match. Select left, returns to left. select right, returns to right.


And, just mebbe the driain plug/s at the bottom of the tank is leaking. if the plugs are still presnt in the respect valence, a bit harder. gotta remove them A story in itsef. If not, just look and feel.


Caveat n spades. Leaking fuel can be the end!!!


Carl

 

The fuel supply system is quite simple, but this being 80s Jaguar, the parts they used can become defective, and then they cause havoc. One never wants havoc when petrol is involved !!

The changeover valve in the trunk switches the feed from the left or right tanks. These can sometimes stick, as happened to me and a light tapping with a spanner or small hammer can get it to move. Trouble is you normally have luggage in the trunk when it does, and also you have to take off the cover behind the spare wheel as well as take the heavy wheel out.

The fuel return to the tank now supplied by the switched tank is by use of a valve in the line to each tank. There is a single line out of the engine compartment to a T-piece near the back suspension where the line splits to run to each tank. Just behind the rear wheel arches are found the fuel return valves. These are handed, and arranged so that when one opens the other closes. Volts to one closes it and volts to the other, opens it.

All three valves are switched from the dash changeover switch that itself can play up and switch some valves and not others. You can see how chaos occurs ! In addition, this switch connects the appropriate fuel level sender. Yes each tank has its level indicated on the dash panel so as it shows near-empty, you can switch to the other tank. In normal running one finds that one tank is almost always empty. Useful if you are passing a garage with a special fuel price on offer - turn in and fill that tank. You know it makes sense !! (lame joke, sorry).

In my own experience, the return valves are those most prone to fail. I never had a problem with the changeover switch, and not much with the changeover valve, I just used the hammer tap if it played up.

Needless to say, all the electrical connections and those terrible Lucas bullet connectors need to be in apple-pie order for it all to work.

Once it is all back to the condition it was in the 80s when it was made then it works OK. Needless to say, Jaguar ditched twin tanks from the XJ40 onwards.