XJ6 & XJ12 Series I, II & III 1968-1992

Fuel tanks leveling out

Old 08-19-2014, 08:04 PM
smgdata's Avatar
Senior Member
Thread Starter
Join Date: Apr 2011
Location: San Jose CA
Posts: 642
Received 58 Likes on 47 Posts
Default Fuel tanks leveling out

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.
Attached Thumbnails Fuel tanks leveling out-photo-1.jpg   Fuel tanks leveling out-photo-2.jpg  
Old 08-20-2014, 03:07 PM
geneo's Avatar
Senior Member
Join Date: Jun 2011
Location: phx/flg az usa
Posts: 195
Received 43 Likes on 23 Posts

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.
Old 08-20-2014, 05:23 PM
Veteran Member
Join Date: Mar 2014
Location: Tehama County, California, USA
Posts: 17,154
Received 3,469 Likes on 2,706 Posts

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.
Old 08-20-2014, 06:19 PM
Roger Mabry's Avatar
Veteran Member
Join Date: Jun 2012
Location: Glendora, CA USA
Posts: 1,270
Received 306 Likes on 245 Posts
Default Get rid of the Jaguar switching valve

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.
Attached Thumbnails Fuel tanks leveling out-six-port-pollack-changeover-valve-new-return-line.jpg   Fuel tanks leveling out-finished-new-hoses.jpg  
The following 3 users liked this post by Roger Mabry:
davidboger (08-20-2014), LnrB (08-20-2014), smgdata (08-20-2014)
Old 08-20-2014, 07:36 PM
smgdata's Avatar
Senior Member
Thread Starter
Join Date: Apr 2011
Location: San Jose CA
Posts: 642
Received 58 Likes on 47 Posts

I'm thinking I should try and find replacements of those brass valves.
Old 08-20-2014, 07:38 PM
Senior Member
Join Date: Apr 2014
Location: Stuart, FL
Posts: 233
Received 70 Likes on 44 Posts

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 following users liked this post:
smgdata (08-20-2014)
Old 08-20-2014, 07:39 PM
Join Date: Jan 2011
Location: Sydney, Australia
Posts: 8,360
Received 3,771 Likes on 2,215 Posts

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?
The following users liked this post:
smgdata (08-20-2014)
Old 08-20-2014, 10:57 PM
smgdata's Avatar
Senior Member
Thread Starter
Join Date: Apr 2011
Location: San Jose CA
Posts: 642
Received 58 Likes on 47 Posts

yeah that's what I'm thinking. might take them out this weekend.
Related Topics
Thread Starter
Last Post
XJ XJ8 / XJR ( X308 )
04-04-2019 02:38 PM
XJ XJ6 / XJR6 ( X300 )
09-21-2015 06:13 PM
XK8 / XKR ( X100 )
09-10-2015 09:37 AM
XF and XFR ( X250 )
09-07-2015 11:13 PM
XF and XFR ( X250 )
09-06-2015 08:20 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Search this Thread
Quick Reply: Fuel tanks leveling out

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: