Hello, got an '87 XJ6 that sat for six months. Just put 5 gallons fresh fuel in each tank.
With power switched on, the fuel gauge needle moves from far left to zero, left or right tank selected. Any ideas? Car runs great, and all selector tank valves are working.
Thanks in advance,
George

 

The changeover switch is segmented. One section works the fueling valves. The works the fuel gauge.

Try wiggling the switch, or very slightly pushing it in or pulling out. If the fuel gauge responds then you have a faulty switch, or dirty/loose connections at the rear of the switch, or dirty/weak contacts inside the switch.

If you have non-arthritic fingers you can remove the trip computer and get a finger into the opening and perhaps just reach the connector at the back of the switch. Give it a push and see if the gauge responds. The trip computer just wriggles out of the dash if you can get your finger nails under the edges

Cheers
DD

 

My 86 gauge reads full tanks whiles there is no fuel as I just noticed that today when I realized the fuel is finished but still right side tank reads full on switch to that side tank.

 

My fuel gauge on my ‘87 reads empty when I first start the car. After maybe 20 seconds, it reads correctly. Is this normal?

 

Yes.

Dave

 

Thanks, Doug.
I jumped the wires behind the switch and got the needle to move. ordered a new switch.
Thanks again,
George

 

First, thank you for the advice. I jumped power to the terminals on the gauge and got positive movement on both sides. A brand new switch resulted in no change. According to the S57 manual, the only thing left is that both tank sending units must be stuck from sitting for so long. I'll tackle that one in a couple of weeks. Need a break!

 

yes probably the senders. Easy to get to. Directly behind each tail lamp assembly. Use brass punch (not steel) to avoid any spark which could possibly result in BOOM !! Open gas filler too.

Remove senders, lube pivots with 3-in-1 oil, exercise them and re-lube them.

 

Thanks Jose. I'll give it a go next weekend.

 

My gauges are lazy, I simply give them a little tap with my finger and they always come on. Try that before anything else

 

Doug, I have a friends 87’ S3 with pretty much the same issue as the OP. I’ve replaced both the fuel tank sending units (rusty), all 3 fuel switch over valves (self explanatory) in the trunk and swapped the fuel gauge with a known good one. I know he’s not opposed to replacing the switch on the dashboard but, I don’t want to throw parts on any car unless it’s beyond repair. This friend of mine is the original owner of the car and has spent an inordinate amount of money getting this car back up to driving condition and I’m trying to help him out when I can. My question is: Is the changeover switch on the dashboard something that can be taken apart and contacts cleaned to see if it works? I’ve taken the window switches apart and successfully cleaned them so I’m relatively familiar with how it works.

While we’re on the subject of fuel, this car has an externally (factory) mounted fuel pump (I replaced it with a new pump last year) and I think the tanks are a little bit too far gone to save. Does anybody have a recommendation for new tanks at a reasonable cost in the U.S.?

 

Thank you for this info. Can I safely assume the tanks have to be fully drained?

 

I don't see why not. The changeover switch is a bit trickier than a window switch.....but that's no reason to avoid trying.

An alternative would be to a thorough dousing of the switch with electrical contact cleaner. With the little red straw on the spray can you can find some slots/openings in the switch to direct the spray right to the innards of the thing so it (hopefully) reaches the contacts

Cheers
DD

 

Ok, got them both to work again. Got access to both sending units. Didn't take them out. just a few strong whacks with a mallet and a block of wood, and they both started working.
I got lucky, huh?
Thanks everyone for your help.