85 xj6
Problem: Passenger side tank is not flowing when fuel switch is in out position. Key on.

Question1: Fuel Tank Changeover Solenoid, How should this be hooked up?
Question2: What tests can I do to diagnose this problem.

In the trunk i had a new Fuel Tank Changeover Solenoid installed.
I am checking if it is installed correctly,
but both Wires are black.
How should this be hooked up?

One wire comes out near the bottom of Changeover solenoid.
He has this connected to WhitePurple lead.
Yes this is 12v when fuel switch is in out position.

And One wire comes out near the top of Changeover solenoid.
He has this connected to the Double Connector with Black lead, ground.
Tested this is ground, yes.

Also there is a small ground strap that is connected to the bolt on base,
other end not connected.

I doubt it is clogged, had the sock filters in tanks replaced.

TestsDone: Fuel switch on dash pulled out, and voltage is 12v and 5.5. OK
Also replaced dash fuel switch, same problem.

As I understand it, all three solenoids are activated when the dash switch is set to OUT.
What I am seeing is this;
Return fuel is pressurizing the Passenger tank.
Fuel is bubbling out of Passenger tank when cap is open.

Now I can only use the Driver side tank.
I drove from NYC to Tampa just using Driver side tank.
Had to stop and refuel every 8 gal.

Fuel tank experts kindly help out on this.
Had car for 20yrs, first time problems with the tanks.

Thanks all,
Brighton Ray

 

It's a solenoid so I don't think it matters, hence the wires are both black.

 

I agree with Fraser on the wires.

More reading:

Fuel Tank Switchover Checklist, Series III XJ6

Cheers
DD

 

The RIGHT tank is NOT flowing when dash switch set OUT position. Drawing from left tank.

Had the changeover solenoid replaced. $$$
But no fuel goes through the RIGHT side of NEW changeover switch.

This is a big problem for me and costing me $$$.
After solenoid replaced, drove from Va to Tampa FL using one tank.

Tests:
Checked voltages at changeover solenoid 12v, s/b OK.
Checked voltages at dash switch 12v, s/b OK.

Question1: There are some junction points between dash and solenoids.
Where are the junction points located, to refresh contacts?

Question2: What should I do now?
Suggestions; _______

Take changeover solenoid out, loosen it with wd40, see how it operates?

R tank is full to brim. Fuel is gushing out of cap.
Drain half and try again?

Question3 Do you think I got a bad part?
New solenoid looks brand new.

Thanks all,
Brighton Ray

 

If no fuel is being drawn from the right side tank I don't see how it can be anything except the changeover valve.

The valve can be mechanically faulty---stuck or clogged. Or it can be electrically faulty---solenoid not operating.

Does the changeover 'clunk' when you operate the switch in-n-out? If so, that would be the solenoid operating. You say that you have 12v at the changeover valve....that's as good as it gets. If you apply and remove 12v and there's no clunk then the valve is dead.....either an internal electrical fault or the solenoid has seized rock solid.

If it is mechanically stuck or clogged then, yes, a slathering of penetrant might free it off.

If it is electrically dead then you'd have to figure out how to open it up for repair.....which might not be possible.

You could reverse the wires and see if anything changes. I don't think it will.....I'm pretty darn sure it won't, actually....but it costs nothing to try and I'd be happy to be wrong.

If it's a new valve it should be covered under a warranty, I'd think.

Cheers
DD

 

Sticking of these changeover valves is fairly common and actually happened to me halfway up a very long hill coming out of Burford in the Cotswolds whilst I had my family with me and all the holiday luggage in the boot ! Having emptied the boot and removed the cover, a light tapping with a spanner got it to click over and off we went.

The filtration in the tanks before the valve is not much, just a metal gauze, so the valve can get a bit sticky with fine stuff that gets through the gauze, or it is varnish due to standing, so probably a clean-out is needed, if the solenoid can be heard/felt operating. Other things that fail are the fuel return valves. If you're drawing off one tank and returning to the other, one or both of these valves needs attention or at least the supply to it. One opens on volts supply, the other closes on volts supply.

I think everybody breathed a sigh of relief when Jaguar gave up twin tanks !!

 

New changeover solenoid stuck.
Voltage OK.

Not wanting to remove unit, BrightonRay needed some external tests.
BrightonRay pressed the hoses to fell pressures.

Getting frustrated, he then grabbed the hoses and flexed the solenoid up and down a bit.
BrightonRay heard a distinct sharp click. First time plunger worked.
It was ok until key turned off, could see R gauge had gone down.
Now intermitten, sometimes off, sometimes ok.

Keep checking it.

Thanks all,
Brighton Ray