Pardon the crummy computer drawing but my digi camera's battery is dead, and figured this was an easier way to get the whole thing in perspective at once.

So this is my best guesswork to see if I have figured out a previous owner's fuel setup:

First off, the car is Series 3 and run by a Chevy v8 with a mechanical fuel pump, so no need for the Jag fuel pump or filter, so they appear to be missing. The thing labeled "weird random box" is just that, a random box that I don't know what it does. It has some electrical wire running into it, and a thick cable but I have no clue what it is, there are no fuel lines hooked to it or no places for a line to be hooked to it.

Anyways, I can tell the 2 big hoses coming through the trunk walls right next to the tanks are obviously the fuel feed lines. The driver side tank connects to a hardware store tee connector, while a hose connects to the other side leading towards the passenger tank, which is just capped off with a big drill bit in the line lol I can tell the passenger side tank wasn't even being used, which sucks because that's the one I removed first It's line is also capped off with a bolt.

Anyways, from the tee connector, a big rubber hose goes along the rear of the trunk wall and turns the corner and eventually connects to a metal hard line right up by the forward wall of the trunk behind the seats. Right next to it is another metal line that's connected to a short rubber hose that's been capped off.

So I'm guessing that a previous owner, who did the swap, did away with the fuel tank switching system and with the hardware store tee connector, just made the v8's mechanical pump draw a little bit from both tanks at once. I would assume that's not an optimal setup because if one tank was empty it would be sucking air and crud along the fuel hoses. I intend on putting a tank selector back in the car so I can choose which tank to run, but not putting the return valves on each tank since being a carbed car, I don't need fuel return lines.

It appears this may be an easier fuel system restore than I thought since I only need to run fuel feed lines off the new tanks and vent lines I guess, and I can save money on return valves and associated hoses.

 

I wouldn't worry about the tank selector valve - with the tee and fresh lines the two tanks will equalize fuel levels on their own. The only concern would be if you park on a steep hill and the upside tank could overfill the downside tank.

 

Agreed.

Makes you wonder why the prior owner did it that way. It probably would have been just as easy (maybe even easier) to tee both tanks together, but instead, he eliminated the passenger side tank. Maybe there was a problem with that tank? It does have sealant in it...

 

I pulled the GMV8 out of my 1984 Jag and installed a 1975 Twin carb 4.2L Jaguar engine. I did a complete overhaul on this motor. Anyway, I have the following setup. the two tanks are connected to each other with a brass tee. Off the tee I have a barbed fitting that goes to a filter, a 3-5 psi electric fuel pump, through a canister filter and into the feed line to the carburetors. At the inlet i spliced the filter shown below and connected the smaller line (the one with the hose attached) on the filter to my return line on the passenger side of the car. This particular filter could also be connected to the two lines in the trunk. I originally connected mine there before I decided to use the return fuel system in my car. This is not really needed as the series 2 engine did not require a return line. I just connected it because it was there. I eliminated the return valves located in the left and right rear wheel wells. Now I have fuel returning to both tanks. At idle I have a good flow through the return. At around 2000 rpm most of the fuel is used up by the carbs so there is only a trickle on the return. As you increase rpm nothing is returned to the tanks. The small fuel line in the trunk has been blocked off as it serves no useful purpose on the carburated engine. I test drove my vehicle on I95 and got up to 110 mph with no fuel issues. I would like to run it flat out to see what it will really do. Maybe I will take Jose for a ride when I see him. FYI; I jacked up the car as high as it would go with my floor jack (18") and left it for about an hour. Both tanks were full(almost). I did not see any fuel overflowing from the high tank to the low tank. I believe the size of the hose and the weight of the fuel in the low tank cancel out each other. I may be wrong, but after an hour I should have seen some kind of overflowing at the lower tank but that did not happen. Don't ask me why, cause I don't have an answer.

 

You guys really think it'd ideal to tee both tanks together and just like it as a single tank essentially? I would think that wouldn't work out but that's just my theoretical thinking...it has been wrong before.

 

You don't have a return line, right? If that's the case, then teeing the two tanks together is a good option. Of course, you have to be mindful of the whole parking on a hill thing.

What are the other options? Putting the change-over valve back in shouldn't be that hard as long as the wiring is still there, so that's not a bad option. Plus it gives you one more button on the dash to play wit.

You could also just run off of one tank, which would be a good option if you only have one good tank.

 

Does anyone know what color wires lead to the original fuel selector valve, and the area the wiring should be sitting? I'll see tomorrow if it's still there and intact so I can see about putting it in. I'd like to keep the valve if I could but if the wiring is hacked or missing, I guess the option is a tee like it has been.

 

Now that you're a Jaguar owner, it's time to get a good wiring diagram. I really like the ones on this page - I think they're by far the best available.

Jaguar electrical reference

This will give you the color of all the wires, as well as the locations of most electrical components. The layout is also very simple, so you can find what you're looking for quickly and easily.

 

Ahh cool reference file, I saved it. However, it says the Fuel Switch info is on page 86-19 and subsection 86-65-39, but on that page, there is no subsection like that. It has the other information on that page that the index says it should, but not that piece of info lol

 

They have switching valves with three ports or six. My S1 with LT1/700R has
one installed with six ports to handle the return to the tanks.

They cost less than $100.00 USD for the six port units and less for the three ports and install easily...

 

Looking at my series 3 the wiring harness comes into the trunk below the trunk latch. The harness contains the antenna wires(3) and two wires for the switching valve. one is purple and the other is white/tan tracer. the other wire is the largest of them all and is white/green tracer. this is for the fuel pump. In addition to this there are two ground wires. You should see a rubber grommet under the trunk latch.Verify that the guy who worked on the car did not push it back into the cowl under the rear bumper.

 

My bad, I should have been more specific. There are a few electrical guides on that page. This is the the one I like:

http://www.captainjaguarscathouse.co...ec%20Guide.pdf

They are in this file, pg 39 & 40 (17.1 & 17.2)