I could definitely use advice for anyone that may have replaced a Series 2 tank for a Series 3 - and how they did the upgrade.


For a 1975 Series 2 - 4.2L XJ6C. My driver side tank has rusted out. In reading a number of posts here, I bought a Series III tank from Spectra Systems - JA1B. I intentionally bought this over a series 2 tank because I wanted the sending unit to be accessible from the rear tail light instead of from the front. This is in hopes of being able to replace the sender more easily in the future. My passenger tank had been upgraded a number of years ago to the same (perhaps from a different provider though).


The problem - the fuel fittings on the new tank are all different from the old tank.


1) Fitting to fuel pump size is different on the tank - my old fitting is too small. There are three holes on the new tank (JA1A). Does anyone know where to buy the fittings that fit this tank? To be clear, the mounting to the car is the same - it's just the fittings so I can hook the tank up to the fuel pump. I am assuming there is a difference from Series 2 (pictured old tank) and Series 3, but cannot find anyone selling the fittings - or what part I'm even looking for.


2) No Air Vent - the old tank had an air vent on the top of the tank - the new series 3 tank has no such vent - but does have 3 openings on the side of the tank - is one of these suppose to support a vent? How was venting accomplished with the new tank?


I'd appreciate any advice. My alternative is to return the JA1A and get the other tank - but then I am back on having the sending unit in the front - and I know these conversions are possible.

 

I just had this done with my car: I didn't do the work but we had some of the same issues you mention.

1. Call John at John's Cars, Texas. He'll have the stuff you need and gives loads of advice. I think highly of him.

2. The venting issue. Ask John about this but with the Series 1 -- which I have -- the venting is accomplished by the chromed petrol cap/housing. I've used my new fuel tank and it hasn't imploded! It might be the same with a SII cap/housing but I don't actually know; John, or others here, will.

3. The tank also requires its own float sending unit for reasons you mention --b/c it sits behind the rear light. This probably came with the tank. My issue is: with original wires hooked up I just can't get it to register on the gauge up front in the cabin. I'll be interested to hear if yours works no problem.

4. There's also the issue of the black tube that runs out along behind the cheap board used as siding in the boot. People here solved that for me and there's an earlier post with really helpful pictures people uploaded.

 

Firstly - thank you series1fan. I am planning on calling John. We have had this car for nearly 40 years, and John had helped us a long time ago if I remember correctly. Thanks for the advice.

I also spent a lot of time last night cruising other forums. I found many similar posts on Jag-lovers.org forums. That is another great source of information. Unfortunately, I saw quite a few posts on this topic, but no one ever really followed-up to explain how they resolved my issue in the end. It is clear though, many people converted their Series 2 tanks to series 3. In a couple of posts, I saw people had done this through SG Barratt. I called them this morning and they gave me a list of parts. I couldn't find a number of them in their diagrams (except for the SIII fuel feeder pipe), so I'm hoping the collection of these solves my problem. For under $30 for everything - it's worth a shot. Other option is to revert back to a new spectra series ii tank.

C336681 (some sort of brass plug - hopefully fills one of my extra holes)
C784 ($0.18 - fibre washer)
C45563 (stub pipe assembly - hoping this solves the main problem)
FS1011 - Union Nut
FS1034 - olive brass 3/8"

I'm looking to get them overnighted. I should have more to post shortly as we get back to trying to make them fit.

I would still welcome other advice. Also - I commit to posting the final resolution to this for those looking to do this in the future.

Thanks,
David

 

One more update. I spoke to John at John's Cars in Texas. He has a "3 piece kit" for $60 he sells to do the conversion. He said it contains 2 Plugs and the proper fuel fitting. He didn't know the sizes. He told me they do it all the time. I asked about the venting, given the new tank doesn't have the vent the old tank had. He told me they basically ignore it. The new tank gets no vent - and they have never had an issue. I ordered his kit too. I will definitely let everyone know what ends up working out when we try and mount the tank again this week with the new parts once they arrive.

 

Hmmm.


Perhaps, I don't get it. The S3 tank is intended for FI cars. Low spigot for gravity feed to the fuel pump in the boot. Upper spigot for the fuel pressure regulator return. one more for the complex over the window and to the front charcoal canister. The latter an emsion thing.


I don't know if your car is a carb car or FI. It does need a vent. Oh, well, if the cap isn't tight and I think many, mine included are not, good enough. lack of a vent of some kind can lead to tank implosion.


As I understand it, sorta, carb'd Jag's don't have fuel return lines.


So, as past mentors have counseled, think it out.


Carl

 

A little history to help - as series 2 tanks rusted out, many dealerships replaced them with series 3 tanks as the old 2s were not available. This had a side benefit of having the gas level sending unit more easily accessible - through the rear tail light instead of having to drop the tank and replace it from the front of the tank. This car has carbs, and about 25 years ago we had the other tank (passenger side) replaced at the Jag dealership. At that time, they upgraded the passenger side tank to a series 3 tank.

As I read a lot of the other threads, there is no issue using a series 3 tank on a series 2. You just have to fill the 2 extra holes for the fuel injection - and get the right fitting for the single fuel line (series 3 is different than 2 in the fitting used).

If the adapters I get tomorrow/Wednesday solve my problem, then this was an easy job in the end (despite all of these posts). The mounting is the same, and I get the benefit of the sending unit being easily accessible.

My only worry is the venting as you point out. Is it really worth the accessibility of the sending unit at the expense of the vent? I'm not sure - but I have been told by many it's not an issue (including John from John's Jag) and my passenger tank has been a series 3 tank for 25 years...

As a side note, I emailed Spectra today to ask about the fittings. They gave me the specs. I emailed them again (but no response yet) to see if they sell the fittings (and bolts to blank out the extra 2 fuel injection holes). See the attached.

 

I saved it all as I plan to replace my very good Series 1 tanks with good Series 3 tanks I took from a '84 Sovereign V12... I will need the return
lines for the upcoming fuel injection conversion.

The good news is the S3 feed lines are larger and that will be useful for the new feed line to the fuel injection and I will use the current feed line as the return...

 

Thanks for your updates here, David. Will be curious to hear the outcome.

I like that Jag-lovers site a lot; huge amount of good info there, but is it now defunct? I can't quite get a bead on how active it is.

 

Ignore this. My mistake. It's been a Very long day.
(';')

 

No, J-l is alive and sorta kicking. Not as active as in past years,though.

 

Good to hear it's still kicking at least. I'll get over there more and see what's going on. There are some fantastic in-depth summaries on there about various XJ issues: these mostly date back though a good number of years so that's why I wondered whether it was defunct. Thanks!

 

I committed to closing the loop on this. The parts I ordered from Johns Cars successfully closed the issue on this. Essentially, he provided the right fitting + two bolts to plug the fuel injection holes. We ran a new fuel hose, which was easy now that we had the right fitting. Now I have a series III tank on a series 2 car.

The question is - was it worth it? Well, if the only option you have is a series 3 tank available to you, of course it is. However, I would advise not going through this pain if you can just buy a series II replacement tank from spectra.

One thing I realized a little late is that the fuel gauge sender on the series 2 is not as difficult to access as I originally thought it was. Yes, it's easier to replace through the tail light (and now both of my tanks have senders accessible through the tail lights). The original series 2 tank required you to remove the wheel - but not drop the tank. There is an access panel near the wheel. It might have just been easier, especially for a carb car like mine, to just have bought a spectra series 2 tank to start. I wouldn't have had to deal with the conversion of the fittings.

Thanks. Hopefully someone finds this useful to their restoration/repair in the future.

 

Thanks Dleckste,
I've just purchase a 1975 Coupe and the sender float has parted ways with the sender. Your posts will be of great help

 

Just a quick note on Series 2 XJ six cylinder cars... (but please take these comments within the context that my training and experience has been on Jaguars in Australia) they are roughly divided into what are considered "early cars" and "later cars" and the cross-over is around mid 1975. This is indepedent to what wheelbase the car is; standard (short) or long. On the early cars there were twin SU fuel pumps mounted externally in the spare wheel well and on these cars, the access hatch in the rear wheel arch allows for changing the sender. On later Series 2 cars, the same rear wheel well hatch is used to gain access to the now in-tank submerged fuel pumps and the fuel gauge sender is now accessible by removing the rear tail lamp assembly. So there are two different types of fuel supply and measurement, depending on whether your S2 XJ6 is early or later - a quick look in the spare wheel well (of a verified unmodified car) tells you what you have:
Twin SU (or replaced by Facet, etc.) fuel pumps = EARLY car.
No fuel pumps visible (and a low humming sound from the selected tank - ear against car with ignition on) = LATER car.
Note that if you are looking at an early paper (or scanned) edition of the parts manual, it will only show the early set-up; the later revisions of the manual show both.
Hopefully that is of assistance when ordering tanks/parts for the fuel system.

 

I just want to say this was a very well explained and informational post. Those members who's cars apply will be grateful.

Thanks,

Dave

 

That is awfully kind of you to say Dave... I am just happy to help in any small way to keep these beautiful machines on the road and giving the delight to their owners that we all crave. Like me, I am sure we have all shared that dreaded moment when the much-anticipated box of parts finally arrives, we open it excitedly, only to discover it doesn't fit after all... ouch! Believe me, it happens in workshops too. It is small nuances like the earlier/later S2 thing that isn't necessarily recorded clearly in the available manuals because originally, the parts manuals were only for the dealership "parts interpreter" and each revision would come in loose leaf form to be added to a ring binder folder - those were the fellows who could rattle-off the part numbers from memory... but they are gone now and knowledge needs to be passed on, IMHO, so I think this is a wonderful, international place to share all our experience and help each other. Have a great weekend!