Does anyone know if the XJS utilizes a voltage stabilizer for the Fuel/Temp gauge like other British cars? On my TR-6 and my old Midget you always knew it was the voltage stabilizer as it would effect both the fuel gauge AND the temp gauge. I don't think the XJS does so yours may just be a comedy of errors where both have givin up the ghost at the same time.

 

I'm not aware of one either. The S2 Sedans did, that I know for sure.

I reckon the fact that the 2 dash units go full scale with earthing the sender wire/s points to the sender unit.

Fuel gauge is more than likely the plastic float has drank some fuel and has sunk, very common.

The temp sender MAY be seeing an air lock, if that cooling system has not been bled properly and/or fully. If the probe is not immersed in liquid the thing will not read.

The wiring is sounding OK, as the gauges moved with that earthing.

 

Thanks for info,my sending unit is bad.when grounding wire,gauge on dash goes to max temp.I found one so I will order it.
Car starts up,everytime so my coolant sensor should be good.
I bled my radiator by the bleed bolt on left side top.I opend it till all air came out,and just green coolant mixture came out.My question is,when car sits overnight,I take off the cross over pipe cap,and looks like the coolant has gone down a little.Is it still settling?I dont see any leaks under car.

 

Yep.

Bleeding some of these can be fun, not.

Many variables involved, especially a car that has been sitting for some time.

There is a hose form the LH header tank, going aft, then disappearing thru a grommet into the cavity. In that cavity is a large black plastic container, called the atmospheric overflow bottle, and it is notorious for filling with mud, and that same hose then sits in that mud, and the syphon back when the system cools does not happen, and mostly air is sucked back in.

The heater tap will close as soon as vac rises, thus ceasing flow thru the heater core to bleed that air out, so remove that small vac hose, block it for now, and let the system bleed that core of trapped air.

The cap on the fill pipe is not sealing 100%. It may NOT leak coolant, but it will SUCK air, trust me, I have searched for that sucker for a very long time in the early days.

The V12 system sometimes just has air pockets, and diligent bleeding, and patience is all you can do.

Remember, every time you lift either cap, you let air IN. Not so bad with that to cap, but it still allows some. Now this is a PAIN on this system, coz the viewing bottle is that sucker made of black plastic, tucked in the wheel cavity OUT of sight. I insert a CLEAR plastic joiner in the hose FROM the LH header tank, TO that bottle, and if there is coolant visible is that joiner, the system is deemed FULL. NO coolant, it is NOT full, so bleed it some more.

On mine, RHD so I got room, I have the atmospheric bottle inside the engine bay, simple, even for me. Its the "Moreys" bottle in this snap.

 

My tip is put a "prestone flush tee" in next to the heater valve. Once valve installed open cap on tee then fill with coolant in the normal way till coolant pours out the open tee cap then have someone replace cap as it's still pouring/coming out. Put the car front "up hill" or on ramps/jacks Then open the bleed port and do same, start car, heat "on" run/pour till nothing but solid fluid comes out the bleed port (shouldn't take long at all if you utilize the flush tee method)

 

Sounds like a lot of good info,I have some clear tubing,Ill replace a good 6" of that hose with it close to tank,for visual and Ill check that atmosphere tank..Also I think a tee is a good Idea..I also noticed on my header tank is only a 7 lb cap,it should be 15 lbs?
now,the vacum hose going to heater core,where would that be located?

Here is some of the crazy things ive been dealing with on this car.I had no power boost on brakes,so I checked vacuum hose at rear of a bank intake,it had a one way check valve in line.The problem was someone had it backwards,so no vacuum was getting to power booster.I installed it the right way,and now I have good power assited brakes.Also someone had air filters in the wrong way,when they are clearly marked.Go figure..
So I hope I dont run into more of the same elsewhere.
Thanks again guy's for the great info.

 

Oh,and what does the warning indicater on dash,mean (Red) looks like lightning bolt? it stays on even with key off..

 

Cap should be 15 lbs. Same on the central cross pipe filler.

The heater water tap is on the firewall top in the centre. You can see the water pipes going into and out of it each side. On the top of this tap is a small tube that the vacuum line should go on to. This closes the water off at certain conditions as activated by the aircon system. There is a second vac line that comes into the engine bay, though a bolted in plate, from where the pedal box and brake servo would be if they were to be on the other side of the car. This should be hooked up to a manifold spigot, and it is this line that provides the vac to the aircon system, via a small vac reservoir under that plate.

Greg

 

Thanks for info Greg.Ill check out vacuum lines today.
the dash warning lights are going crazy.The warning light above the alt charging gauge,stays on all the time even when key is off.As I mentioned in previous post.It looks like lightning bolt..Is that for alternator not charging??Also if one of the long rectangular lights in middle is lighted.whats that mean?

Oh and one more item,there is a cable with two adjuster nuts on the end,looks like the throttle cable,but little bigger.It comes from firewal left hand side and goes through a big eyelet at rear of brake fluid reservoir.Its pretty long.It must go somewhere??

 

anyone out there?

 

The cable is probably the cruise control actuating cable. Maybe this mechanism has been removed from the V in your car?

The alternator is probably failing/failed, or some other charging circuit failure. This light is the 'not charging' light. The long horizontal light strip below is also illuminated when a serious fault happens, to further draw the driver's attention to the fault light.

Greg

 

ok,so I guess a new alternator is in order,and yes the cruise has been removed.I guess ill just tuck cable away somewhere.
I also noticed my TPS is changing every once in awhile.I have to keep resetting it.
I guess moral of this story is to buy these cars,running and driving,not when they have been sitting for years.
thanks for info.

 

According to the owners manual the left light with the image of a battery is>>> XJS H.E Handbook mode on >>>> "VOLTS" "Illuminates to indicate battery overcharge (malfunction of alternator) >>>Mode off>>>the lightning bolt light on the right is according to the manual an>>> mode on>>> "Ignition" "Illuminates when the ignition is switched on and should extinguish when the engine is running. Should the warning light be on , stop the engine and investigate the cause">>>XJS manual mode off>>>

FYI...My "batt" light (on the left side) will also come on with an "undercharge" condition.

 

ok makes sense,but it does stay on all the time.even with key off and out of ignition.
I did find a wire that runs down the right side of inner fender well.Acording to my wire diagram.it is brown with black tracer.It reach right across to alternator.It says thats where it goes so i hooked it up to connector on back of alt.so now once I get car running again ill check that battery indicator.
I went out to car yesterday and tried to start it,and it did try to start a couple of times,but died right away.
I put volt meter on tps dc volts with ignition on. and it was fluctuating while I was trying to start car.
So with volt meter hooked to tps,set on volts,and ign on it was reading .39 v and reading erratically as I
was crancking eng.When eng finally started (rough idle) before it died in 3 seconds.the volt meter was all over the place.at idle.so with ignition on ( not cranking eng) I jiggled wires going into tps around and it was changing the reading every time,sometimes 0.00v.And when theres any vibration or movent of wires. So Im assuming tps is bad.?

 

Yes, it's bad. If you have the large black TPS under the capstan, they are no longer available and they are prone to fail after a few decades. The newer style is red, but you have to buy a fitting kit to get them on, or modify the capstan spindle and build a spacer to activate the newer style TPS.

Or, go to a breaker and buy a capstan that was made for the newer TPS, and then fit the new TPS you have bought to that, even if it has a TPS on it already!

The wire to the alternator is the exciter wire as well as the warning (I think), and I also think that the alternator will not work if it is not attached. Someone knowledgeable will confirm/rubbish this rumour; Of course the alternator may still be bad, wire attached or not!

Greg

 

That TPS is toast.

As is one I rescued on Friday.

I rang JagDaim in Melbourne, and the TPS they now have is a "direct fit" to the 3 leg Bourns that is in there now.

The price I got was $270.

If this is as stated, sweet, as the fitting kit "was" about the same $ a few years back. The owner has put the Jag on hold for a while as he is off o/s for a few months, so I wont get to replace it until he returns.

I used a s/hand XJ40 TPS on mine 16 years ago, and made my own adaptor kit, and it still works just fine.

 

thanks for info guys,I figured the tps was the culprit.Every time I would try to start car the eng would shake just enough to move wires and setting.
I found one for 145 but like you said need the kit also.I'll check around,a bit and see what I can find.If I can find a s/hand one that works ok,ill get it.for now,moneys a little tight right now.well see what happens..
So for right now the car sits till then..

 

Get a hold of David Boger at everydayxj.com he breaks an occasional XJS and is super nice to deal with and super AFFORDABLE. Non-better in the used XJS/XJ6 parts world.

 

This is from an old thread reply by Doug Dwyer...may be of some interest and I'm sure Doug could shed some further light on it for you.

"The original was the "Bournes" TPS. As far as I know all the replacements for it are "brand x". The one I bought only lasted 6 months...maybe I just got a dud. I think later red type is higher grade.

If you like little projects and have 2-3 hours to do some minor fitting work, you can use a $30 TPS from a '1992 Ford Mustang 4 cyl. If that interests you I send along a few details" DD

 

thats strange I was just looking at that same post from 2013.
I was going to get you guys opinion on it.It does save a buck,just as long as I dont screw up the modifications on it.
But willing to try it.Thanks
Is there an actual page on the subject somewhere?