Dear all

I did the throttle body clean, and all has been good since, but yesterday I did an 80 mile round trip, having stopped briefly at my destination, to complete the intended task there. When I got back, I stopped, to unload, and the car would not restart. No way no how. I thought, this happened a few weeks ago, and leaving it for a while resulted in a restart. This week however, there was no restart. Initially there were attempts to restart, spluttering and burbling, but it would never run. The car on this trip and the previous referenced one had driven perfectly, until I stopped. Today, I tried again, and there is no attempt to start, not even a murmur. Turns over beautifully, but does not fire.

If I listen very carefully, with the garage door shut, so I can hear all noises, I can hear a pump running, in the engine compartment, but no pump running behind me, at the tank. From reading, I should be able to hear this one too, I believe, but I hear nothing. What's that best way to tackle this. Fuses in the engine compartment all check out, as do those in the boot (trunk), but I don't know about the relays. I'm just going to check which one needs to be checked and then see if it's working. The pump in the engine bay seems to run without stopping.

In the meantime, and I have tried to search, but I never have much luck, is there a walk through for changing the pump, if it turns out to be that? I read somewhere, in the last few weeks, that there is a valve in the fuel line somewhere, to check to see if it squirts out. If I recall, someone comically said, if it squirts you in the eye with a good blast of fuel, then you probably have good pressure. If it dribbles out, then you do not. I scanned around but didn't find it. Where might this valve be? Probably in the walk through, but as I said, I can't find similar. Is it something that a relative car novice can undertake?

Anyway, if I can leave this with you, those of you who know how to search the site better than I, I'm off to check the relay.

As always, thanks very much.

Cheers

Sutty

 

I just swapped stop lights with the fuel pump relay, and still had stop lights, so the relay must have been fine. Fuse 7, 20A, is also fine. I checked them all yesterday, but thought I would double check.

 

I tried to increase the volume of the noise in movie maker. Hopefully you can hear it here.

I also tried to feel for vibrations at the tank, whilst starting, but felt none.

 

Duplicate post, sorry. Please delete.

 

Back again, sorry. I did find the Shrader valve in the fuel line, thanks to a post in this forum. When I depressed it, nothing at all came out. Can I assume that if you have just attempted to start it, the lines should be pressurised, from the rear pump, and it should squirt fuel from there, or do I have to be starting it, whilst depressing it? If so, I will have to recruit Mrs S, lol. Does that valve represent the pressure in the line, only from the rear pump?

Also, is there any way to introduce fuel, to confirm start and run? Can it be introduced at that valve, for example?

 

If you turn the key to the second position 'ignition on' you should have fuel pressure. The pump will run for a couple of seconds and then shut off until the engine starts. It would appear that you are dealing with a failed pump or a severely blocked fuel filter. But the filter being that bad is unlikely.

 

Thanks, I thought as much. I considered the fuel filter, but dismissed it on the basis that I have only 37K miles on the car, and that the car was working perfectly, until I stopped and then it simply wouldn't start again. Not that unusual for something to give up the ghost, precisely when you power cycle, but far less likely for the fuel filter to become instantly totally blocked, I would think.

I tried the ignition in position two, three or four times in a row, because I read that it can help, and all I hear is the pump in the engine bay. I'm assuming that runs and runs, as you might have heard on the video, until I turn it back off, because no fuel arrives to achieve the correct pressure/flow for after that pump? I'm sure I recall hearing that only run for a few seconds at most, when operating normally.

Is there any way to absolutely confirm, because I don't really want to do all that work, and buy the pump, only to find out that it's something else?

Does what I've found so far seem definitive?

No pressure at the Shrader valve.
No rear pump noise, when turning to position 2.
Doesn't smell of fuel from exhaust, after multiple failed starts.
Engine bay pump runs indefinitely, or at least for a long time, in position 2. (I haven't let it run too long, in case running dry may cause an issue there.)
Car was running perfectly, on an 80 mile round trip, until I turned it off.

I'd love to know if there is a specific test though, other than what I've described above.

Thanks again.

Sutty

 

I'm not a mechanic by any means but I have replaced two fuel pumps so take my advice as you please. It sounds like a bad fuel pump to me because I believe if you had your trunk open in a quiet garage you should vaguely be able to hear it run for about 10 seconds when switching your ignition to position 2. Also Im not sure how to save you the work but if you want to test it you can remove it and test it with an external power supply just be sure you're in a well ventilated area with proper personal protection and connect the wires away from the gas and more importantly the gas fumes, otherwise it can explode. My guess is that the pump needs replacing though. Good luck!

 

There is no fuel pump in the engine bay, only in the fuel tank. The humming sound you hear comes from the throttle body.

You can test the fuel pump if you remove its relay and plug two longer wires (that you can bring to the fuel filler neck) into the relay sockets shown as 30 and 87 on the drawing below. First, verify that you have power in the socket 30 by connecting a small bulb between the wire and the ground. If there is power at the socket 30, listen for the pump sound at the filler neck while touching the two wires together. You don't need to switch the ignition "on" for this test.

 

Oh yeah, if I tested it, it would be done safely, but thank you for the sensible advice. I'm glad you agree it's likely to be the culprit. Like you say though, no way to test it without having done the bulk of the work. Having already done it twice, how difficult would you rate it, and did you have a guide to follow?

As for the quiet garage, it was very quiet, door down, and I have now repeated that with the liner removed, having had Mrs S turn the key for me, with my head in the boot, in case it only ran for a short time. I heard nothing, other than I could still hear the one at the front. Also placed my hand directly on the tank, and felt no vibration.

 

It seems like the best way to test it would be to use M. Stojanovic's way.
And sorry I didn't clarify but both fuel pumps were not on XJ's. I replaced a mechanical fuel pump on my 75 Chevy K20 in my sister's driveway the first time I ever did it and it took about 25 minutes, then I later replaced an electric fuel pump in my girlfriend's BMW 750il and I would say that was equally as easy it took me about 30 minutes. However both of those were easily accessible, on my truck it's on the pass side of the engine and my girlfriend's BMW had an access hole that you could just unscrew in the trunk and then just lift out the whole sending unit.

Edit: this might help
https://www.jaguarforums.com/forum/jaguar-xj8-jaguar-xjr-27/i-think-my-fuel-pump-toast-51597/page2

 

Dumb question, I know. When the key is in position 2, how much fuel is showing on the gauge?

 

I missed m stojanovich's reply last night, so thanks for that, and sorry for not replying at the time. It was late for me. Maybe the posts came in close together, either way, sorry and thanks. I thought it sounded like a pump at the front, but whatever it is, I'm fairly sure it used to stop, and now it does not, so I think that's a change in behaviour. Thanks for the clarification though, I'm learning all the time. I'm kind of pleased there is only one, because that means there are fewer points of failure, for a complete lack of fuel flow. I had put my hand on various bits, and determined that the noise came from near the throttle body, at the front, but I couldn't say precisely where. It actually felt strongest from a device right next to the throttle body, but it doesn't matter now, if there's just one pump in the tank, and I have no pressure, then I'm getting nearer.

Thanks again m stojanovich for laying out the test with such crystal clarity. I was considering that test as I drifted off to sleep last night, but I didn't know quite how to go about it. I was thinking, if the relay makes the pump run, and I can work out which wires do which thing at the relay, then I can simulate being the relay in the on position, and make the pump run. Telling me which are the contacts that get made, and that it will be live without ignition, is a great help for doing this, and makes listening very convenient. I'll do it today.

Kroeger's jag, I'll have a good look at that link once I've fired up the pump from the relay terminals.

Addicted to boost, the tank is over 3/4 full. There was plenty in anyway, but when this happened, I thought maybe, just maybe, if I filled the tank, the extra height of a fully filled tank, might help the pump move the fuel through. Forlorn hope I know, but it was worth a shot. I have many petrol operated devices that require me to have petrol on hand, so as it happens I had four gallons available to add. I did this, and it is well over 3/4 of a tank now, but it changed nothing, other than I now have more fuel to remove, lol.

Right, off to listen by jumping the relay, and then to get the fuel out.

Cheers

Sutty

 

Made a jumper lead, with spades, and plugged it into 30. Checked, and had battery voltage, bar 0.01V. I then put the other end into 87, and my battery voltage did not drop, at all. I heard no noise, and felt no vibration on the tank body. I then moved round to listen at the filler cap, and even pushed open the spring flap, for even more unrestricted sound travel, but still I heard absolutely nothing.

I think that's as definitive as it gets. Thanks m stojanovic for that test, and to all the others, who helped with suggestions. I'll have a read around now, about the best way to replace it. At least if I decide against, and get it done at an independent, I will know exactly what it is, and cannot be blindsided. Want to attempt it myself, so hopefully I will find a really good guide.

Jumper in place, below, nothing!

 

if and when I have to change my fuel pump, I will do it from top (someone's write-up I found is also attached as pdf):

 

Thanks for that information. I'd already found a you tube video, showing that method, but there's no way I'd hack the metalwork away like that, as I mentioned higher up in the thread. Also, I learned today, that I am not prepared to work under the car. I wanted to remove the connections that are under the tank, but I could barely even see them, was frightened to death the whole time I was under there, and I simply wasn't prepared to do it. Right now, I don't have the correct release tools, but I don't need them now, because I won't work under the car like that.

I put it on good quality axle stands at the rear jacking points. I left the Jaguar jack in on one side, just lightly tight, and a hydraulic jack at the other side, again just barely touching, so the weight remained on the axle stands. I put two ramps in place, so if the axle stands, and the jack or jacks failed, it could only drop down a fraction, onto the ramps, but even with three methods of support, on each side, I felt very uncomfortable. I'm convinced it was totally safe, 100%, but I couldn't convince my subconscious brain of that, so I was far from at ease, even for just looking. Pulling, tugging, and straining on things, whilst under there, and I would freak, so I didn't even try.

On the bright side, I did see the fuel filter, but I'm not prepared to change that either. I guess I need a pit digging in my garage, lol.

I'm going to release the brackets now, and see how much it will move, if any. If I can tilt the top out into the boot, without forcing anything, I will press on and do it myself. I believe others have managed this. If I can't, then it will have to be collected and repaired.

I'll report back on my success or otherwise.

 

Well I didn't try overly hard, or for overly long, because I couldn't move it very far without resistance, and I had no idea how hard I could pull. I could move it, so I could deal with the weight, and it was loose, but as I pulled forward, enough to where I could begin to tilt it, it got harder. Could have pulled much harder, but I had no idea how or what it was pulling on, so I abandoned it and put it back.

On the bright side, maybe I'll get a slightly cheaper repair, having cleared out all the boot area stuff, such as CD changer, spare wheel, carpets, filler neck rubber seal freed off, etc. I hate failing at repairs, but this is beyond my level of experience. Top down, would probably not be, but I don't think I can bring myself to hack into the car like that. I'm pondering it now, but I'm fairly sure I'll opt for repair.

Damn it.

EDIT: Oh, by the way, I checked wiring to top of the tank, by disconnecting the pump coupler, and checking for battery voltage when I jumpered the relay again. It worked, so I know I had relay switched power getting that far at least.

 

PLEASE do not try to pull the tank into the boot area without removing the fuel lines under the tank!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

WHEN you bend/kink them and they leak or stop flowing fuel, you will need to replace the parts that are NO LONGER AVAILABLE!!!!!!!!!!!!!

Many sad stories here in the forums!!!!!!!!!!!!!

I always charged 4 hours labor to replace the 4.0 XK8XJ8 fuel pumps.(a little extra for SuperCharged)
I have done DOZENS and DOZENS and it is not that difficult. (at least for me)

 

Yep, I get it, thank you for the clarity of thought. I didn't try very hard, it stopped moving so I stopped pulling. No way I pulled hard enough to bend anything, but warning fully taken on board, thank you. Useful for others too, I imagine, to see it repeated clearly.

I think I could do it too, if my subconscious brain wasn't screaming, 'get out, get out, get out'. I doubt I'm going to be able to overcome that fear, of being underneath. It was irrational, it was safe, but irrational fears are just that. People have irrational fears, phobias, of all sorts of things, and there's not much can be done to overcome them, because by their very nature, rational thought does not work. Today, I discovered I had one.

Maybe tomorrow I'll try again, and create an entire structure under the car. Doubt it will help, but I can try.

Thanks again.

 

Nope, can't do it. Cannot go underneath the car without an overwhelming sense of impending doom. Best part is, I wiggled under with it on the ground, just to see. No room to work of course, but there is just enough clearance to get in and probably not be squished to death, but it doesn't make any difference, that's rational thought again, I cannot stay under when it is up on axle stands. Frightens the bejesus out of me.

I've contacted my local independent, who has a good reputation. Annoying that I will also have to arrange separate transport for it, because they don't do it, but that's life.

Maybe I'll get a discount for having stripped everything back, and for putting it all back in myself, afterwards, leaving only the tank portion to be done?