So to start off let me apologise that it's yet another "won't start" thread, honestly I've read pretty much most "won't start" threads and followed every bit of advice that's been given so I'm posting this in the hope someone can point me in a direction that I haven't followed yet.

I purchased a 1996 XJS 4.0 automatic celebration from auction, it was listed as not running but was confirmed by previous owner that It does run and drive but had a fuel leak.

Upon receiving the car I put 5 gallons of fuel in and fully charged the battery, tried to start the car and it turned fine and sounded like it was trying it's hardest to "catch" and start but just wouldn't.

When turning the key to just before start I can hear the fuel pump prime for 2-3 seconds and hear the relay click in the engine bay, when trying to start the pump doesn't run (is this correct?)

I inspected the car fully and could not see any obvious signs of a fuel leak anywhere this is where I noticed that towards the front and back of the main fuel line had been replaced with rubber hose and that the fuel filter was no where to be seen (from what I've read it's behind the passenger wheel under the cover) this was just a straight pipe from tank to rail. So I installed an inline fuel filter

Next I removed the crank position sensor which was covered in gunk, cleaned it all off and put it back, no change and still registering around 200rpm when trying to start so I don't belive that is the culprit.

Read about flooding the engine so pulled the fuse for the fuel pump and held foot on the accelerator whilst cranking the engine a few times and then left it for an hour or so. Upon trying the engine again it now just turns and turns but doesn't even try and "catch"

Checked the insertion fuel cutoff and that is fine

I pulled the coils and checked for spark, 1,2 and 3 sparked ok but 4,5 and 6 had nothing, checked coil 4,5 and 6 with known good plug and it sparked fine so decided to replace all 6 plugs with bosch R6 (which were the same as already installed) all 6 now spark. Checked compression (albeit crudely) in all 6 at the same time and they all seemed good and consistent.

Upon doing this I was hopeful it would now start, unfortunately back to the same engine turning but not even attempting to catch.

What I have noticed is that after cranking a few times when I open the fuel cap I get quite a considerable "woosh" I'm not sure if this is normal from just cranking the car?

I've now given up for the night, put the battery back on charge over night as I fear the amount I've been trying has drained it considerably.

So my question is, what have I missed? When I crack the fuel line to the injectors I get a little spurt of fuel but nothing major, would this be a sign of a problem with fuel pressure? What worries me is the lack of fuel filter that was previously missing, could something have blocked the injectors? Or blocked some sort of fuel non return value causing a loss in pressure?

If you've got this far I really appreciate any help or advice you could give and I apologise for the essay but I'd really love to get her running.

 

hi- sorry you are having problems with your car.

If your crank sensor has perished, as they all do in these cars, and certainly at this point, cleaning it will not do. You will need a new one. That is typically the first solution to the “no start” AJ16 engine

 

Thank you for the reply, so even though it registers 150-200rpm when trying to start it could still be duff?

 

yes- and as this is a maintenance item, I would suggest you replace it even if your car was currently starting normally.

 

Oliver,

Your description of an apparent vacuum being created in the tank could be symptomatic of a collapsed breather pipe. This can also cause reduced fuel pressure. Try cranking the car without the tank cap on.

Having said that, I'd also be suspicious of the crank sensor.

Good luck

Paul

 

Ah ok, so if I crank it with the tank cap off what should I be expecting to happen/hear? I'll be sure to try that tomorrow though.

OK just had a look into them and can pick one up for around £20 so not too bad, at least I can rule that out if I put a new one on.

 

Oliver,

The whoosh you're describing is air rushing into the tank as you release the vacuum that has been caused, impacting the ability of the fuel to be pumped up to the engine. You won't hear anything with the cap off, but the fuel might be able to pump easier.

At £20, I assume you're talking about a used sensor?

As it's an AJ16 engine, if you want some bedtime reading, have a look here:

https://www.jaguarforums.com/forum/x...-120221/page2/

Cheers

Paul

 

Ah, that makes sense, I will give that a try tomorrow thank you. The breather pipe you mentioned that might be collapsed where abouts would that be and is it just a piece of pipe or is that some sort of return valve that could be blocked inside?

It says its a new Lemark sensor, it's on ebay item number 362759569017 looks exactly the same

Thank you, I'll have a good read of that.

 

Hi Oliver

I had exactly the same problem as you on my 1995 Celebration Convertible, She wouldn't Start and I tried everything including wasting £50 on a New Crank Sensor, that I didn't need!

It must have easily taken me 3 Weeks to Sleuth it out

Where I finally managed to do so, as having run right out of ideas 'Paddy' came to the rescue

When it turned out that the cause of my 'No Start' problem, was down to one of those 'Blue Hella Relays' which are just above the Fuses underneath the Knee Pad on the Passenger Side of a (UK) Car

Because it seems some Relays can have Thinner Blades than some other makes, where it doesn't take to much for these Blades to lose Contact in their Holders, so what I did was to Swap it out for the other Blue One that was in the Holder next to it

I don't think that the Relay was dud but more a question of not making Good Contact, so I well have got the same result by removing the Relay and then Plugging it in again, although it could be better to Swap it out with one with 'Thicker Blades'

Just make sure that it is of the 'Same Value' and also bear in mind that the Relay you are 'Swapping' has a 'Diode' which as such is not interchangeable with a Relay that hasn't got a Diode

So try that Relay 'Hack' first and see how you get on, as this was 'The Last Trick In The Book' and the one that worked for me!

I also had a couple of Blocked Injectors, which I also mention in this Fix, together with how I tested and replaced them which hopefully you may not need to do

Also if you want to Test the Crank Position Sensor, unplug the electric plug and then put your Meter probes on the plug, while you Crank the Engine and see if the Needle flickers and if it does it 'may not be the Crank Position Sensor but you MUST have your Meter set on AC (handy tip from 'Warrjon')

If you want to read the 'Saga' which has everything from checking the Plugs and Injectors and replacing them as well as Cleaning the Contacts on the ECU and doing a Compression Test and lots of other Stuff, including removing the Fuel Tank and Replacing the Fuel Pump 'It's all here'

Including Lots of Photos of everything I did, which may be of help: Link Below

'Carmen Won't Start' Trying every 'Trick in the Book' to get my 1995 XJS Celebration Convertible Started and the last one Worked!

 

Oliver,

Further to OB's very helpful suggestions, Jaguar quote different part numbers for the sensors fitted to the AJ6 and AJ16 engines. I don't know what is the difference but that ebay one is claiming to fit all 4 litre engines whether AJ6 or AJ16. So, maybe worth investigating first to see if AJ6 sensors will work on an AJ16 engine. You can also test your existing sensor by measuring the resistance.

Good luck

Paul

 

Gentlemen (and ladies) SHE RUNS!

but...... (there's always a but)

So I tried starting her with a fully charged battery, no dice, same as before not even trying to "catch"

Removed the fuel filler cap and tried again, same as above.

Reluctantly used a little bit of easystart and after a few cranks she fired up, and ran under her own steam with a little bit of throttle, unfortunately as soon as the throttle is released she cuts out.

Really pleased to hear it actually start and honestly I don't think it's started for a long time (have a feeling the previous owner bent the truth)

So now onto working out why it won't idle, any clue before I start researching the new problem?

 

Oliver,

Well done on getting it started. If you feel that it may not have been running for some time, then it's quite feasible that you've got a couple of injectors that may be slightly gummed.

A cheap way might be to put two bottles of injector cleaner in the 5 gallons that you've got in the tank, start her again and run for 15 mins with various throttle openings and see if you're getting any improvement at all in its ability to idle.

Cheers

Paul

 

Take off the throttle body and clean it. Plan on using up a can of carb cleaner and some rags.

Taking it off requires removing the four 10mm bolts, and some electrical and hose connectors...and the sneaky small hose on the underside of the throttle body. You'll make a little bit of a mess taking it off if you're not ready for it. I usually jam a golf tee in there, and tighten up the clamp. You'll possibly need one for the hose going out as well as in.

This is something you can absolutely do yourself.

And before you ask, no, there is no gasket between the throttle body and the intake manifold...even though there looks like there should be.

 

So managed to spend a little more time on her this evening.

So, put another gallon of fuel in (High octane) and a bottle of injector cleaner, first crank she almost started and ran but cut out. After that she again just refused to go "catching" almost every time.

Tried full open throttle and primed the pump 3 or 4 times and she fired, ran for about 10 seconds giving it some throttle but slowly gurgled to a stop, tried a few more times after that and it started every time but eventually cut out so I'm almost certain it's a fuel issue.

Unfortunately didn't have time tonight to clean the throttle body but that's on the list next.

Is there anything else I could be missing aside from CPS? Could the fuel pump itself be on the way out? Could it be blocked injectors? (obviously it won't run long enough for the injector cleaner I put in to work at the moment)

I will update further tomorrow and thank you all for the help.

 

I'm wondering if it is a failed fuel pressure regulator? Having low fuel pressure would give the symptoms you describe, I can't remember if there is a port on the fuel rail of an AJ16 to measure fuel pressure.

 

Hi Oliver

It's beginning to sound like you have some Blocked Injectors

In which case it may be better to take them out and Clean them, which is easy enough to do

You can see how I did it here:

Removing the Coils and Spark Plugs

Doing a Compression Test

Removing The Fuel Rail

Cleaning the Injectors

Replacing The Injectors

Your No Start Problem could also be related to the Coolant Temperature Sensor and how to Test it is also included with lots of Photos

Removing the Coils/Cleaning the Spark Plugs/Doing a Compression Test/Removing the Fuel Rail/Removing the Injectors/Testing and Cleaning the Injectors/Replacing the Injectors/Testing the Coolant Temperature Sensor/ As well as lots of other related stuff

 

oliver,

this is my opinion and my opinion only. I am no expert, but like to think I know the eccentricities of an AJ16 motor pretty well:

Change the CPS - THIS IS A MAINTENANCE ITEM!! If you want a reliable car that will start with no problems, this part should be changed, even if you where having no problems at all. Even if it does not fix your problem, it will not be wasted money.

Same goes for the CTS. It’s a 30 or 40 dollar part delivered from Jaguar in the UK. I don’t think it’s going to prevent the car from starting, but you should not be running around with the original one on a car that’s traveled that many miles.

There are many parts that you can’t just “bench test” and can only go by instinct and some luck. TPS is another one of those. They make AJ16’s fail at speed in scary way, making them “black out” like the car just died as you are increasing or decreasing throttle. -but I digress-

invest on a CPS if you plan on keeping this car and driving it

 

I think the fuel injector theory is a good one. Wouldn’t be the first time that someone went through this ordeal only to find out 2 or more of their injectors were fried.

Send the injectors our to a cleaning service. It’s not too expensive, just takes about a week to send them out and get them back.

Judging by your progress, it may not be the throttle body after all. (But that needs to stay on the to do list anyways)

The Coolant Sensor will likely not be the issue, but if you’re not sure, take the harness off if it and jump the two ends on the plug together. (Leaving the sensor on the engine alone)

It could be a dirty or faulty MAF?

I have yet to read about a fuel pressure valve going bad on a car. You can test that by pulling the vacuum hose off it it and seeing if there’s any fuel leaking out of it.

There is no port to test the fuel pressure at the rail....or anywhere, on the AJ16.

 

Thank you for all the above advice

Fuel rail and injectors are on the list tonight and while I'm at it I'll probably clean the throttle body

Spike apologies I should have mentioned that I have ordered a CPS, just waiting for it to arrive and I shall replace it.

Just waiting on a price for air/oil filter from jaguar (luckily I have a friend in the jag spares department)

I plan on spending more time on her tonight and hopefully I can progress further again, when she's up and running ill be sure to put a few pictures and she's been unloved but I plan on bringing her back to her former glory.

 

I hate to be thinking like this but perhaps someone "spiked" the gas on the previous owner. You never know what reason someone is selling the car or what the story was, jealous girlfriend or boyfriend, angry person, who knows.
I say crack the fuel line in the engine compartment and take a sample of pumped fuel in a glass bottle a see what it looks like. Locate the fuel pump relay and energize it and let the pump run the old gas out. I just have a feeling something like that is preventing good running and perhaps what might still be in there might have clogged your injectors too.