My 77 xjc has a completely different fuel line system then the sedans.
From what i have tracked down, I have the in tank pumps. No hose's in the trunk at all, i cant seem to find any cross over valves or anything like the sedans.
Well what i do have is a hose coming out of the tanks with some brass valve thingy, then the hoses become one, which then precedes to a filter next to the carbs and that is it.
All that the switch does it switch from right to left etc...

My tanks are leveling themselves idk if its those brass things or what but after i fill up one tank the next day or so the tanks now have the same amount. its kinda funny


Any ideas from fellow "C" owners.

 

My 77 C also has in-tank pumps and a factory push button, that changes color when depressed, for switch over. I can run one tank dry.

 

My tanks were plumbed together at the time it was converted nearly 30 years ago. However it draws out of the left tank twice as fast as out of the right one and they don't level out. I wish they did, because one of these days I'll run that left tank dry, and since air flows easier than gas, I'll be stranded.

This is yet another project I need to fix this coming Winter.
(';')

 

You can fix tank switching problems - with or without return lines by using a modern switching valve...Pollak (6) port with return lines or the same valve with (3) ports if no return lines are needed. This is the version used on my '71 Jaguar with a carb and no return lines.

In the attached photos, it shows it hooked up to my old '72 Jaguar with LT1 V8 and the high pressure electric pump was out of the photo on the right hand side of the spare tire well for that photo.

The finished version shows the fuel pump on the left hand side with longer hoses that allow the spare tire to fit easier. It shows the new bulkhead fittings for the return line and feed line. Installation is easy and the six port valve is around $100 USD. I have the wiring diagram available for any interested parties. Two relays are used as in the photo.

It has worked perfectly for several years now and will allow you to run either tank down to the desired level (should only be 1/4 for electric fuel pumps). Note the clear fuel filters from the tanks used before the pump. Works with the stock fuel senders and Jaguar gauge.

Today, there is also a high pressure can filter inserted into the feed line for additional filtering... cannot have too many in Jaguar fuel system with the caps facing up into the weather.

 

I'm thinking I should try and find replacements of those brass valves.

 

don't know if it helps, but the marine industry uses all sizes of ganged valves in brass, to link multiple fuel tanks. Look online at a chandlery ... might save some money.

 

The brass valves are non-return / check valves? At least that's what i'd expect them to be. If one or both are no longer functioning correctly it would explain why the tanks are levelling. Maybe they just need a clean out?

 

yeah that's what I'm thinking. might take them out this weekend.

 

If this is a '72 I am to believe that there would not have been any return lines (because carbs) and you had to add them to the tank? I have a '74 and am trying to figure out the return set up. Did you discuss this build on a previous thread, or do you have other helpful pics on how you tapped into the tanks. I really like your truck valve set up, I may have to copy it!

-K

 

I changed the S1 tanks to later model with return lines.

 

Thanks, still debating what to do....

 

So here is a (frustrating) phenomena that I encountered... I built a fuel set up similar to Roger's post on 08-20-14, things were working great until I sucked down the right tank, (unknowingly) and then when I switched to the left tank (with fuel) the pump went air bound. The situation did not resolve until I put fuel in the right tank. I assume it had something to do with static head pressure and positive displacement pumps yada yada.... but I thought the Polak valve would solve that. Anyone else have similar experiences, how much fuel do you need to keep in a tank.... etc. ????

 

I keep 1/4 fuel in my tanks, at 1/4 I fill back up....do not run them dry... plus low fuel means pump gets hot.