Fuel return valves Series III XJ6/12
 

Had a fuel return valve fail. No big deal. Decided to replace both sides at the same time. I already had a brand new RH valve that's been in one of my Jag-boxes for so long I can't even remember how or when I acquired it! Had to order the LH valve, though

I've put up a couple of pics. First, those unfamiliar with the return valves might like seeing the pics. They're located in the rear wheel wheels behind a metal shield. The shield can be seen in one of the pics.

There was a minor problem, though. Not of any real-world consequence, but annoying.

The LH valve doesn't match the original. The mounting bracket isn't the same length...which prevents utilizing both mounting holes. You'll see this in the pic. This was a new part, Jaguar part number in a Jaguar box...not a brand-x aftermarket replacement. A bit disappointing.

The RH valve, also Jaguar OEM...the one I've had for years.... is an exact replacement, right down to the "Tecalemit" decal

Cheers
DD

Damn. Pics came out wrong. Imagine them rotated to the right. I'll try to fix

Cheers
DD

Trying again!

Cheers
DD

Thanks for the informative post. I have a few questions. Yesterday I bought a beautiful 87 SIII and everything runs beautifully..... until I stopped at a gas station to fill up. I opened the left tank and there was this big whoosh of air. I opened the right tank and gas spewed all over. This indicates a failed fuel return valve, correct?

Regarding the photographs. The metal plate is in the wheelwell, where do I look for it, above the tire, forward wall? Please advise. I have to drive it home from California to Ohio so I am assuming I can just run on the right tank (where the fuel is returning) and I will be fine. Do you agree? I hate to pump gas on the road all the way home.

BTW, during my pre-purchase test drive I tested the tank switch and they seemed to switch between tanks fine. Apparently not.

Jeff

Just went out and started the car, opened both gas lids, used a pencil and flashlight to see what is going on. Fuel is always returning to the right tank regardless of the fuel tank selector switch position. So I plan on drawing only from the right tank, when it gets low I can switch to left and effectively pump gas from the left tank to the right. I think I can get home doing that and I'll straighten the whole thing out when I get home.

the returning of fuel from left to right tank is one problem, Doug will explain that to you.

the swoossshh when you open either filler cap is a separate problem, i will answer that:

there is an inline check valve at the front inner fender behind the tire. This check valve is supposed to OPEN when vapor pressure exceeds a certain calibration, but it doesn't, causing a buildup of fuel vapors in the tanks which make the tanks expand and contract until they start leaking at the seams.

the vapors are supposed to go through this check valve on their way to the Charcoal Canister, and from the canister into the engine compartment where there is an electronic Purge Valve that opens and allows these vapors to be burned by the engine. That is the way it is supposed to work but the Check Valve gets in the way.

The solution to eliminate the buildup of vapors at the tanks:

Remove the Check valve and push a drill bit on one side and pull it the other side. This will break the inner membrane that prevents vapors from moving through it. Reinstall the check valve and no more swwoooosssshhh.

This solution has been around since the late 1980s. There are no negative effects.

I agree with Jose; two problems.


The plate is towards the rear of the wheel well...likely partially obscured by dirt and/or undercoating. So, if you remove the left wheel and look straight ahead, the plate will be slightly towards the right. And if you remove the right wheel, it'll be slightly towards the left


Yes

Cheers
DD

so the questions arise: why would the newer LH valve be different at the bracket? Are there other Twin Tank cars that use the same valve? Daimler maybe? Are these valves used for other purposes in other cars?

the different mounting must be because of a different car, no?

I would be very annoyed by receiving a part that does not match the original.

A one-off mistake, perhaps?

At some point Jaguar apparently stopped using Tecalemit valves and went to another supplier...who perhaps got the specs wrong?

I dunno.

Cheers
DD

Thank you gentlemen. So to get home, I drive on the right tank, when it is low, open the left lid to relieve pressure, drive far enough to pump gas to the right and then repeat? I assume that cracking open the gas cap will be fine (if not ecologically correct) as long as I don't take off too fast on an uphill grade. Do you agree? Thank for your help. Sacramento to Reno today.
Jeff

Sounds good to me

If you hit rain make sure to close the cap :)

Cheers
DD

Annoyance is such a variable.

I'm sure Doug will make an adapter or drill another hole and bolt the thing in place and proceed to the next issue.

Jose:

Your solution surely is time tested. But, is not a working one way valve a trifle more elegant. As I see it, the piecing merely allows a miniscule vacuum leak!
The engine manages just fine anyway...

Picky picky, Guilty as charged.

Carl.

Carl, you can use a hose-to-hose splicer/connector that accepts different sized hoses, as I did in my car, since the check valve has two different sized orifices and hoses going to it.

Regardless of whether you pierce the check valve or use a splicer, the buildup of fuel vapors is eliminated without any side effects.

Below is the variable splicer I use.


https://cimg1.ibsrv.net/gimg/www.jag...e0a341f7db.jpg

My left tank makes a "bong" sound when in use and a "swoosh" sound whenever I open the filler cap. I gather form the internet that non-US spec Jags do not have the Charcoal Canister. What could possibly be my problem then? Many thanks Jose :)

what year is the car? Maybe someone eliminated the charcoal cannister? Have you checked to see if there is a Check Valve inline with the fuel vapor lines coming from the tanks to the engine?

Hi Jose, the car is 1984. Bought new in Malaysia and usually it is the same as a UK specs car. How does the check valve look like? Is this the one that is kinda hexagon in shape, almost looking like a large pencil (i.e. see pic CAC 2028)

https://cimg0.ibsrv.net/gimg/www.jag...4555ca2215.jpg

Yes, some cars bound for less emmesion stringent markets do not have closed loop venting

Merely vent to the atmosphere as of olden days.,

I kinda like the cannister thing.

Carl

Thank you, Jose, for your clear instructions on fixing the fuel tank whoosh problem. It was even easier than you said. I thought I was going to have to jack up that corner of the car to get to the pressure relief valve. I got a flash light and bent over and took a look to see what I was dealing with. It was right there and no clamps on the hoses. This is the new pristine 87 so I assume it came that way. I slipped on a pair of latex gloves, grabbed hold and out it came. I cleaned it up, drilled it out and popped it back in. As a bonus, since I cleaned off the road dirt, it now looks like a brand new valve.

As for the fuel return problem, I took out the boot carpet and removed the panels so I could see what was going on with the changeover valve, pump, filter, etc. Everything looks like the day it left Coventry. Clean enough to eat back there. I went through the stack of receipts the PO provided and found that all the fuel system components in the boot have been replaced along with new rubber hoses. So, probably no problem there. I peeked behind the rear wheels and could see that the return valve on the left had been disturbed but the one on the right covered in road dirt and undisturbed. So that is the next project.

BTW, as you can see the Kent wheel in the boot is brand new. One of the diligent PO had replaced the original tire as it was beyond its expiration date.
https://cimg0.ibsrv.net/gimg/www.jag...396f1ada35.jpg

you welcome! no more fuel vapor buildup to damage the tanks!

try to find the original
fuel return solenoid made by Tecalemit, they were Jaguar suppliers since the 1940s.

if you find it, please share the part number and vendor, I need one too but refuse to buy the aftermarket.