Ok so I got to go work on my 93 xjs and bolted my neutral switch back up. It still turns over, but wont start. I tried listening for the fuel pump (after unhooking the door open buzzer smh) and when I turn the key there is a click from the trunk area (I think the pump relay) but I dont hear a buzz or anything. I tried activating the inertial switch and the click didnt happen, then tried connecting the wires, and got a click, but thay was it. Also I decided to try shooting a little starter fluid in the throttle body to see and it didnât make a difference. I pulled the one plug wire and put a good plug in it and tried turning it over, but it showed no spark. Could this be happening because of my security system? Is there a way to run the pump and get spark if it is the issue?
Can you disconnect the fuel rail at the engine?
Use a catch can & lots of towels and briefly turn the key to âONâ.
I had a âno pumpâ condition on my 94.
My solution for the six months until I found the solution was a hot wire.
This was from the battery direct to the pump wire.
I was fine unless I forgot to unplug the hot wire when done.
There were many times I returned to a dead battery.
Eventually, a Jaguar expert I knew studied the wiring diagrams to find the issue.
He called me the next morning and asked me to try changing the fuse for the HO2 sensor.
It started right up.
I donât know if the 93 and the 94 share this configuration, but it might give you somewhere to start.
I did try disconnecting it, and fuel came out, but when I tried turning the key, nothing came out. I wouldnât think the amount that came out would have been there if the pump wasnât working at least sometimes. The last inspection ran out in 2014 and I dont think it was really run since at least then. I will have to look into the h02 fuse (also what it is! Lol)
Its an O2 sensor in the exhaust pipes. Some are heated and if the fuse feeding this fails it cuts power to the fuel pump.
Ah ok! I thought it might be an O2 sensor, but never really thought about them having fuses! duh on me! Ill look up where its located!
So looking at my owners manual it shows it should be in my right side rearward fusebox. Which oddly shows its a 12 fuse block, whats odd is that my right rear one only has 3 fuses which the manual says should be the left rear? I havenât looked at my left one yet, but am wondering if itâll be the 12 fuse block.
To further elucidate, the HO2 sensor is heated oxygen sensor.
If the sensor is not being heated, the ECU will shut down the fuel pump(s).
Not sure if it was one or both pumps.
Is your xjs an earlier edition than 1994, a convertible or right hand drive?
All variants could affect the location of the fuses.
For some unknown reason I recall the #9. #9. #9. #9.
Mine is a 93 convertible, I looked at my owners manual and it showed a fuse, but I donât have the block they show and I dont see the fuse listed on any of the other panels, also looking at the wiring schematics for my year they show a relay vs a fuse, however looking i didnât see it and on other forum posts they say it gets its power from the fuel pump relay! ARGH! LOL! I did get to try to diagnos my no spark and have found that my coil is bad. My CPS resistance read good all around, and when trying to start with my coil tower plug pulled from the dissy cap it wouldnât spark when cranking. Checked voltage at the coil, key off no voltage either side, key on voltage both sides. Good resistance between positive post and tower, Zero resistance between positive and negative posts! Ah ha! So to ask has anyone used a coil with an internal resistor?
I would never try to advise someone about the configuration of any car but a 94 coupe.
Having a location diagram that doesnât match you vehicle does not surprise me.
There was a lot of changes during that period, especially the electrical layout.
You should try to find a diagram specific to your VIN, if itâs available.
Never assume anything is logical on any Jaguar.
I had to make many copies of the wiring diagrams so I could mark them up.
Ya live and learn:) I have not come across them as being described as Ho2 always heated o2 
You guys with your convertibles have it easy.
Arenât the fuse block and relays in the boot right there above the battery box?
On my 94 coupes the relays are hidden tucked up behind the boot side panel.
Not only that, they are way back where you canât even see them.
I forgot if there are five or six.
Except for the fuse blocks behind the bolsters, none are labeled.
So say you need to check the fuel pump relay, out of the line of 5 or 6 relays that you canât see, three of them are for relaying the two fuel pumps. Two fuel pump relays on the RELAY LOCATOR diagram are different for coupes vs. convertibles, 4.0 vs. 6.0, RHD vs. LHD, are #1 & #2. I seem to recall the schematics say the fuel pump circuits are #A & #B.
I didnât mention the third relay because I donât ever remember seeing it on the circuit diagram. BTW itâs called the MAIN fuel pump relay.
What happens if the xlijhdf PO didnât like the arrangement, because the FP relays which he had to test were ALL furthest up the chute, so he rearranged them?
Some where up in Coventry there is an xede8ysedf engineer laughing at us.
If he could have heard me curse him while trying to figure it out, he would have spontaneously exploded.
Mine are above the wheel arch too, but I only see 2. I got my new coil and have spark! Yay! Itll try to start with starter fluid, but no fuel in the line, although I think I hear a brrrrrrrr sound sometimes when i turn the key. You said about hot wiring the fuel pump, where did you hook it to? I should say, did you unhook the relay and just hook a wire to the âlegâ of the relay? I would like to try just to see if it works. Also i had an issue with the boot coming down on my head lol, fixed that today with new struts! Lol
This is a procedure I used on my 94 coupe.
When I hot wired my fuel pump, I disconnected the black, two prong connector, on the right side, where the harness goes behind the side panels near the top of the boot.
While you are there you should closely inspect that connector.
They have a reputation for corrosion, which causes them to overheat, melt and die.
On these cars there should be a warning,
"every time you disconnect a wire, add some dielectric grease when reconnecting."
I took the disconnected harness that goes to the tank and I made a temporary bypass harness with two spade connectors, some stout wires with alligator clips and ran both clips straight to the battery. In retrospect, I should have connected the pos side to a key on circuit, so I would not have to remember to disconnect it.
As a reminder, this is a procedure I used on my 94 coupe.
I donât have any clue to how your 93 is wired.
Do yourself a favor and get a wiring diagram for your car.
Ok thanks! Thatll give me a start! I do have a wiring diagram or two or three lol, I didnât know if you had just hotwired the red/blue wire to the battery or both ground and power. I am going to have to look around up in there, like i said i only see 2 relays and they are kinda dangling there from the PO looking for issues smh. The one relay he had in had the cover off, so I put in a known good relay. Needless to say they are both tan Jaguar relays now so I am going to have to look at the wire colors smh. I feel Im soooo close to getting it running, I just want to verify whether or not my pump is actually âworkingâ or not. From what Iâve seen, it doesnât look like the security system would shut down the fuel pump, and I think the security system issue may be a moot point since I have spark when I turn the key. Anyone know if I âjust unplugâ the security system, if the car will start and run? Ive looked at the schematics so much my eyes have gone buggy, but I think the only real issue is the âstart inhibitâ relay which almost looks like you could almost just splice the wire around it
Jason,
I know what you are facing, I had several conflicting wiring diagrams when I had my fuel pump issue. It took an actual Jaguar Expert, with enough experience and the curiosity to bring the work home, to study the diagram and solve the problem.
All my diagrams were not original and were sometimes/often illegible.
That connection I suggested to look at, was a known culprit, in facelift cars. We had a few that came in to us, where we found that connector melted, and the insulation broken down where this resulted in either a short or a gap in continuity. You would have expected this to result in catastrophic fires, but no stories were reported as far as I know.
Itâs that connector where I unplugged the connector and ran my jumpers to the battery.
Oddly enough, If you continue tracing the wiring towards the tank/pump, there is a smaller white connector at the top of the tank, with lighter gauge wires.
Itâs here where you would expect an overload, before the one that does melt.
The 5 or 6 relays in question on the 94âs, have a bracket with relay tabs, welded to the outside of the black wheel arch brace. They line up on that bracket where all the wiring from them go forward or back. The fuel pump wires go forward around that bracket and turn left to the tank/pump. They should never just hang unprotected. You should be able to feel around for them easy enough.
I canât recall a start inhibit relay on any cars I worked on.
There is one other thing to check if you find the fuel pumps are running and still have a problem. When I suspected the fault was inside the tank, I removed the tank and found a few of the hose clamps were loose. Right before that, I did pressure check the tank which could have pushed the hoses off the lines, but NOT loosened the clamps.
I donât know anything regarding what the security system does re. a âno startâ condition.
Also I canât tell you what will happen if you unplug it.
What is âsmhâ?
Before I disposed of my donor car, I saved all the components I could.
If you need any relays, or anything, let me know. I donât remember any tan relays though.
Give me a heads up as soon as you are even thinking of buying any parts.
Cool lots of good info thanks! Smh=shake or shaking my head. As for the two tan relays, I must admit that I went to the junk yard and there was an xj8 that I took all the relays and fuses out of. After testing them, as I checked the relays in the car, as i found a bad one, I would swap in one of the good ones. I know thats can cause possible problems when looking for âblue base with black relayâ but i figure to get it going a good relay thats the wrong color is better than a bad one of the right color
Ok Jason, just remember I have all these things if needed.
Ok thanks! I will keep you in mind if I come across something
Does the '93 have a crank position sensor? If that fails it prevents spark.
It does, I do have spark now, after testing components I found it had a bad coil. Everything else tested out fine. Thanks though