Shawn, Is that working ok? Tee'd the returns too? Fuel injected or carbs?

 

yep did that as well and so far so good we haven't had any problems.
fuel injected.

 

Fire due to stuck change over valve? Well, that's another thing to lose sleep over.

 

You won't have a fire if one of your return valves stick, resulting in no return path for the fuel......... as long as your entire fuel system from the pump to the regulator can handle 90psi/max pump output fuel pressure :-) At this rate of fuel pressure the car should hopefully stop itself from severe over fueling. Ours didn't but then it doesn't have closed loop Fuel Injection with O2 sensors as yours does. If you want to be 100% sure, fit a fuel pressure gauge.

 

As this seems to be generating some discussion, here is the actual set up we are running in the car today :



Parts list :

2x "Tee pieces" https://www.summitracing.com/parts/SUM-220636B
2x "One Way Valves" https://www.summitracing.com/parts/SUM-220192B
2x "male/female adaptors" https://www.summitracing.com/parts/FST-30274-1

Performance :

Each sender works correctly, and pushing the fuel selector switch still shows you left hand and right hand tank level (obviously if all is well they should be running at approx the same rate). I can brim both tanks and usually the amount to fill the tanks is within 1 gallon, ie the feed part is feeding from both tanks reasonably evenly. I can park on hills and not worry about one tank feeding through the T-piece and overflowing the other tank as the one way valves prevent that. I have no electrical items in my fuel system that could either stop the car or spill fuel if they failed.

 

What I've seen happen is one tank get's over filled from the return, fuel still coming in finds path (under pressure) through the tank evap hose and up to the charcoal canister, fills that up and you have fuel pouring out of the canister vent and on the ground under the front fender. So, prob the changeover valve stuck with the other tank selected. You don't know this until you smell raw fuel after stepping out of the car.

When you have fuel pouring out the charcoal canister and you go open the filler cap on the full tank, you get a fuel volcano.

 

Yes, we had all of that. Our tank filler cap seals were not too good so we had fuel escaping out the filler and running down the rear fenders and onto the exhausts......also not cool. In the end the only way to stop it doing it was to "T" the tanks together. Haven't had an issue since.

 

SARC that diagram looks really promising. It looks like though, that if the car were parked for a long time with one tank high that the other could overfill via the tee'd return. Am I correct, or over thinking this?

I'll tell you though, I'm ready to do this on my '86. I've had fuel out the charcoal canister more times than I'm comfortable with. About 6 months after I got the car, my daughter wanted to drive it to high school. So I replace all the fuel valves, put in a freshly cleaned and coated tank on the right and cleaned the recently replaced left tank. Put in pre-pump filters in the back and took apart all the lines and fuel rail and cleaned everything. She drove the car two years with practically no problems! Then it broke a starter nose and I let it sit for about nine months ...bad idea! Got it to the shop and put on a new starter and drove it a couple weeks and then as I parked it at the shop one day I found the dreaded fuel pouring out the damn canister again, right hand tank under pressure. Haven't felt like digging into all the valves again and cleaning everything out. So it sits high and dry on the back concrete slab looking really pretty. Been about three months now.
I could get motivated though thinking of tossing the valves and teeing the lines.

 

How (where) did you tee the return lines?
I'm doing this, this weekend! I think I have two one way valves. I'd love to drive the jag again!

 

Remember the return lines go into the tank from the very top, just below the filler neck, so getting fuel to flow back down the return lines would be extremely difficult, so I wouldn't be too concerned about that. If you were really paranoid, you could add another 2 one way valves in the return line, similar to the feed line but we don't have that and have tried the parking on a hill thing with no negative issues.

Our car is an S2 V12 Coupe, which originally had a rather unique return system where the return line goes into the trunk, then is split or "T''d by a 3 way valve which, in theory, diverts the return fuel to either the left or the right tank. I've lost track of what your car is, but if it's an S2 with the 3 way valve in the return line in the trunk, like ours, then you replace the valve with the "T" piece. Here is a picture of our set up in the trunk.



The feed line, with the one way valves can be seen at the top middle of the picture. The return T can be seen at the bottom.

You can compare this to the previous iterations on the system we did.

"Rev 1" was simply replacing what was there (2x 3 way valves, 1 feed, and 1 return) with new parts --> Didn't work..... had constant tank overflows



"Rev 2" Replaced 3 way return valve with 2x 1 way return valves (similar to S3 cars) --> Didn't work..... had constant tank overflows



If yours is an S3 car, your return line is already "T"d somewhere. I believe it's under the car just ahead of the rear cage. The only thing you have to do physically remove the 2x 1 way return valves which are in front of the tanks, accessed through a panel in the rear wheel arch.

 

I use the Pollak (6) port valve for fuel injection or the (3) port valve if still carbed.

It works flawlessly and allows you to keep the inside of the car stock looking and work properly as designed. Gauges will read properly and fuel is returned to tank being used for feed...simple and MODERN and not Jaguar.

The first picture is the finished installation, but it does not show the Pollak valve..it does shows the new inline fuel pump for the fuel injection. Valve is about $100 USD and is used in many vehicles by Ford.

If the wiring diagram is not clear, I have a Power Point that I can send you to you... it would not attach here?

 

@Roger

Good suggestion. I looked at your post when we were struggling with the overflowing, and I was tempted, but by that time I had already spent a lot of $$$ so I went the shortest route. Do I understand it that the 6 way valve is 2 separate 3 ways valves that switch over at the same time ?

 

I want to wrap up this restoration thread for a few reasons :

1. We have a usable, enjoyable car which, although not perfect, is a huge improvement from where it started 10 months ago when we first got the car. Essentially it is no longer under intense restoration, although a 40 year old Jag will always need something worked on, but hopefully the pace can be slower now.

2. We have another very interesting project to kick off (which was spawned from this XJ12C restoration thread) so we will be focusing on that, and will start a new thread for it.

3. I wanted to reflect on the journey we've had, as many say the journey is as important as the destination.

Overall Summary : We paid real $$$ and took a big chance on a car that hadn't been started for over 20 years, but, due to the honesty of the previous owner, we came out of it in great shape. From a cold, calculating, monetary perspective, if you take the purchase price for the non-running car, plus shipping (Ohio to CA), and all the parts we have put into the car, I am quietly confident I could sell the car tomorrow for a profit. This is obviously not counting the considerable hours/days/weeks/months myself and @smgdata have put in to the car. Selling the car was never part of the plan, but there's some satisfaction in knowing you didn't just pour money down the drain.

Nasty Surprises List :

1. The rear cage was in a real mess. This required a total rebuild which was a great learning experience for me as I hadn't done one before, but was a lot of dirty, heavy work whichever way you look at it.

2. The gas tanks were badly rusted on the inside, no doubt from being stored half empty. The good part about that is we have replaced every single thing from the filler cap to the injectors, so we know we have a good baseline now.

3. Despite multiple attempts, and much money spent, we could not get the twin tank switch-over system to work properly. We are now running the 2 tanks combined, which is working fine, but there is always a niggle remaining when you don't know why something didn't work.

Pleasant Surprises List :

1. We did a lot of work on the ignition system and distributor, all at the same time. The safe thing to do would have been to do things in stages, so if something didn't work you can easily trace the issue. In the end, after 1 full weekends work, and with every component in the middle of the "V" replaced, the car fired up on the first try, and ran noticeably better than before.

2. The car passed CA SMOG on the first attempt.

3. Almost everything we did to the car "stuck" on the first attempt, and the only thing we've had to do twice was replace the alternator belt as the first replacement failed after a few weeks.

Overall impressions of the car :

I don't know what it is, but there is something very special about these cars. In terms of looks, you always look back at it as you walk away......... The pillarless design is timeless and elegant, and the experience with all the windows down is very pleasant and frankly a lot better than a convertible. Our color combination is also a plus point on the aesthetics. This car is different in feel and performance from the other Jag V12s we have. The jury is still out on exactly why that is (steering rack rates, spring rates, suspension set up, wheelbase length, seating position ?) We don't know, but we know we like the way the XJ12C goes.

Still on the "to do" list :

1. The starter motor needs replaced. We have a new gear reduction one ready to go in.

2. Re-cover the passenger seat, same as the previous post.

3. We need to replace the front windshield seal. We recently did the rear one as it was much worse, so we are taking a break before doing the front one to let our nerves settle. It's nerve racking handling these pieces of glass knowing fine well you can't call Autoglass or similar to replace it if you break it.

None of these issues prevents the car being used, so the plan is to rack up some miles on it and get it dirty. None of my cars are show cars, so the XJ12C has to take its turn in providing real life transportation.

What did we learn :

1. Even a shiny car that looks good needs a lot of work to bring it back from a 20 year slumber, even if it's been stored properly as ours was.

2. Two of us working on the car helped a lot. At certain times (ie rear cage) it was pretty much mandatory, but at other times, when one of us was having a bad day and getting stuck on something, the other was there to help out. We naturally gravitated to things we did best, which ended up being very complimentary. I am more about cosmetics, anything electrical, as well as coming up with ideas for tasteful (we hope) modifications. @smgdata is a lot more mechanically inclined, has mastered A/C systems, and is very talented at sourcing parts.

3. These days with the internet, forums like this, YouTube videos, etc, you can learn pretty much anything, and with places like Harbor Freight (at least here in the US) you can buy almost all of the tools required to do jobs you would probably not have considered doing before. Welding and A/C work being the ones that come to mind immediately.

Self Work vs Shop Work ratio :

The car was in the shop on exactly two occasions. First was for the SMOG check. The second was for the custom muffler system. Harbor Freight doesn't sell SMOG machines or industrial pipe benders, so we don't feel too bad about these times when we had to pay someone else to work on the car.

I hope the info we provided on the thread will help other forum members if they approach the same jobs we did. I tended to document Coupe specific things in detail (headliner, seats, side window seals) as the documentation in the ROM was usually very sparse about anything Coupe specific. It was always satisfying to post a write up, then get thanks and acknowledgement from fellow forum members.

Who do we have to thank ?

Too many to mention, but Grant deserves a special call out because of his intense knowledge of this era of car, which got us out of trouble multiple times.

It will be sad to see this thread drop off the first page of the forum as it has been there for 11 months. With over 200 posts and over 14,000 views, hopefully its been useful and things can be found in future using the search function.

Do watch out for our next thread which will be starting soon. If you like rescuing Coupes, you're going to want to follow along.

 

This thread is extraordinarily useful.
Thanks for the time and effort you've put in to writing it.

PS you can always add to it if you find something else to document.

 

Thanks for the kind words. It makes it all worthwhile.

We will have plenty new things to learn and post about Coupes in the other thread, trust me on that!

 

Well, this thread has been a Major reason to turn on my computer every morning since you started it.

I will certainly be checking out your new thread, because even though my car isn't a coupe and doesn't even have a Jag engine any more, all the other bits Are Series 2 Jaguar, and I've found your posts not only helpful but Very informative; besides being Just Plain Fun!!
(';')

 

Yeah, me too. But, I merely let this machine slumber, rather than shut it down.


Two schools of thought there.


The one way valve on each tank seems to avoid side slope over flow
problems.


But, I kinda like the tank switch thing. So far, so good, it works.


I wonder if my 85 FI Ford had the valving Roger uses. It had two tanks. But, unlike the Jaguar method, if one went dry, the engine continued to get fuel from the other....


Carl

 

Thanks so much for this thread SARC. Info like this in invaluable to present and future coupe owners, and all early xj owners. Your time documenting your journey is much appreciated.

 

Carl, I'm going to look into the ford fi thing, very interesting that it would pull from the other tank without manually switching it over.
Thanks,
Bill

 

I've really loved being able to join in vicariously by way of this thread. I've enjoyed learning more about these cars, reading your entertaining prose and, of course, leveraging your experiences as you've shared them along the way. You two have done something fairly heroic (2 guys restoring a car in a garage in less than 11 months with only 2 visits to a professional) and you should both be proud of the results. Can't wait to see the car again. Thank you.