Any one have an idea how to trace a fuel leak without taking the car apart?
I have a slight smell of gas when driving with the windows down, and a strong whiff when I open the trunk.

 

check the spare tire compartment with engine running.

look at the fuel filter connections with a flashlight to see if anything is leaking, and the same all around the compartment.

do you get a strong whhooosssshhh when you open either of the gas filler caps?

 

Two possibilities that happen to me:
- Fuel pump started leaking from the housing
- Fuel tank changeover valve got stuck causing the gas return to only go to one of the tanks despite the tank switch selection which resulted in an overflow condition.

Both of the above in the trunk.

In the front, I had one of the fuel injector lines rub against metal which eventually caused the rapture of the hose. Now that was scary.

 

Thanks Jose. There is indeed a strong whoosh when I open the left filler cap. What does that indicate?

 

Jimmy, it means the Fuel Vapor Pressure Relief Valve located in the vapor line before the charcoal canister is not opening or "purging", a typical problem with the Series 3 XJ.

if you can hear the tank(s) "contracting" when this happens, (sort of a metallic sound as the vapor is released when you open the gas filler cap), it means that fuel vapor pressure is building up and expanding the tank walls, eventually this expansion-contraction makes the tank(s) start to "stretch" the tank seams beyond their limit, and the tank starts to leak.

since you are smelling fuel, one of the tanks is suspect if no leaks are found inside the trunk. Check under the tanks for any gasoline stains.

To resolve the whoosh vapor pressure buildup once and for all, find the check valve by raising the front passenger side of the car so the tire goes down as far as possible;

look at the inner wall until you see a black plastic check valve similar to the one in the picture below attached to the wall and connected with rubber hoses on each side;

pull the check valve from the hoses; Take a 1/8" drill bit and push it through either hole in the valve, pulling it out the opposite side hole; Reinstall the check valve observing that one side goes to the larger diameter hose.

This will eliminate the vapor pressure buildup whoosh forever, yes the car will pass inspection, no it will not affect the engine performance.

 

Great info Jose.
I wonder if that return valve will be there, as my XJ has an LT1 motor.
We shall see...

 

check the passenger side wheel well and report back.

 

As does my 83. I merely plugged the line from the GM canister into the LT1's purge valve. Works just fine.


I have a spare canister that came with my "engine package". It looks amazingly like the
one in the Jaguar. The hose hook up diagrams are close, but not quite.


The filler lids on my car are far from fume proof.


Carl

 

Carl,
the evap system in the XJ-6 is/was from GM, another GM system in the XJ-6, just like the Delco Air Pump system, like the Harrison a/c compressor, the Delco Ignition Amplifier, ad infinitum....

 

Found the evap valve behind the rear wheel, having difficulty getting the clamps off, but I will persevere.
Question:
1. When I do get the hoses off the Fuel Vapor Pressure Relief Valve , should fuel be coming out of either hose? I have the system depressurized.
2. What is the unit next to the fuel pump at the rear of the spare well, that looks like a motor, and has a drain hose?

Also, found my leak at the tank switchover unit, but will have to drive some as I have 2 full tanks, and probably need to drain them somewhat to get that unit out no? The hoses don't look to be too easy to clamp off without damage.

All help really appreciated...

 

behind the rear wheel? clamps?

hold it! that does not sound like the check valve I'm talking about. I meant the one located in the FRONT passenger side wheel well.

no fuel should come out when you disconnect the hoses from the valve, only vapor from one side if you did not open the gas filler cap while disconnecting it. If fuel is coming out, you are disconnecting the wrong valve.

 

Pretty sure I'm at the correct valve, going by the Haynes manual.
How about that other unit I asked about Jose?

 

You are correct Jose, I was looking at the fuel return valve...apologies. I'll look tomorrow for that evap unit...
why oh why can I not just pay attention?

 

ok, no problam, but stop everything and download the Factory Service Manual. Donate the Haynes to charity.

Go to: XJ6 / XJ12 How To quick links here in this forum to download the Factory Manual for the Series 3. It's free.

post a picture of the item you are referring to, if I don't know someone else will. you have a 1983 which is very similar to my '84 built in Sept. 83, but I can't visualize the part you are referring to. Thanks.

 

I'll grab a pic later today, when the temperature by mid afternoon will be high 60's as opposed to 26º now.
Not sure if I can find a charity to take the Haynes.

 

My charity for the Haynes would be the brown can that my waste servicer company picks up. Paper, glass tin, alloys, etc. for recycle.


Or, as one has suggested, to correct the wobble on a table that is too short.


Actually, it does have useful stuff. just hard to find as the "organization" is awful


The series 3 stuff is just "jammed in" as an insert, sorta.

 

Fuel return valve is part #CAC 3939.
Advice on removing the fuel tank switching unit without draining the tanks?
It looks like my fuel leak is at the connection out of that unit, which works fine.

 

Of course, next question, what to use to clamp off the fuel hoses without damage?

 

since you depressurized, (smart move), very little fuel should come out, and what you do is remove the old part and reinstall the new part as quickly as possible, using gasoline-proof gloves.

I use a product called "Hylomar" used in racing cars to seal gasoline hose connections.

 

Done in about 30 sec, so grateful.
What a waste of effort on the wrong valve yesterday.
Going in on the fuel leak at the switchover unit now, thanks for the tip on the "Hylomar"