Hi Guys

No experience of working on these 6cyl AJ16 Engines but my XJS won't start

Fuel Pump working and plenty of high pressure petrol flow to the Fuel Rail

Also a really good Spark on all Six Spark Plugs

If I put a bit of petrol down the Air Intake, She will run (She was running ok yesterday but for a very short while)

So it would seem that Petrol is not being injected into the Combustion Chamber

Not familiar with the Fuel Injection System on these Cars

Any Ideas what might be the problem and how to fix it?

 

OB
No real experience of the 6 cylinder, but try following the injector leads to the loom plug and give the plug a clean? No idea if it uses a resistor pack, but if there is one, clean that too. After that, maybe clean the multiplug that goes into the ECU? Which I think is under the passenger toe board and requires moving the carpet and a bit of wood to get at it - at least it does on the 3.6.!

 

Hi Greg

No dice, unfortunately so I'm thinking the Injectors will have to come out or maybe a new Crank Sensor

 

When cranking, it the RPMs don't go up to 200, then the crank sensor is determined to be at fault, no? Is the tachometer needle moving when cranking?

It could also be the camshaft position sensor, no? I'm not sure there is a way to be certain without trying it out.

The fact that you got it to run with fuel in the intake concerns me. Can you keep it running with your foot on the gas, or does it peter out either way?

I suppose there's no check engine light.

Assuming the car is being underfueled because when you add fuel to the intake, it ran:

Can you check to make sure you have a working MAF? If thats dead, it won't start.

Can't think of a way the Coolant Temp Sensor would prevent the car from starting. Jumping the harness couldn't hurt.

Oxygen Sensors are ignored until they get hot. Can't see how that has anything to do with anything.

TPS is read, perhaps that is malfunctioning?

Can the IACV prevent the car from starting?

Lastly, check for corrosion on the ECU. That's a common occurrence, and can easily be the culprit.

 

Hi Vee

Cheers!

I'm not familiar with the 4.0L Six but I've got a few more checks to do including some you mention, including the RPM when Cranking, which should have been the first thing that I checked

So thanks for reminding me on that one

 

I had something similar and it was simply flooded. Pull a few plugs and have a look, blow out the cylinder with compressed air if the plug is wet, just to displace the fuel and reassemble. Do the cylinders one at a time, as it's easy to get the coil pack wiring mixed up on the rear 2 cylinders.

 

Hi Jagboi

Cheers!

That could be worth a shot

 

Has the crank sensor ever been replaced as far as you know? I am thinking that the crank sensor sets the pulse for the injectors but could be wrong about that. I had a crank sensor fail on my '95 with no warning-car ran fine-shut it off and next time cranked over but would not start. It has been a several years now but I believe I did have spark and fuel pump working when the crank sensor failed. I found out that the tach will pulse very slightly when the crank has failed even though many at the time did not think it would.

If the crank sensor has never been replaced as far as you know I would recommend starting with that as the magnets get week over time regardless of miles on the car. They are very easy to replace and right around $100.00 for a new one so if it is getting old I would replace it as good insurance to start. I tried bench testing my failed one but could not get correct readings to tell if it was good or bad so luckily I had my other '95 and switched it out and the car started right up.

Hope this helps but if you have not had any issues with the running of the engine before this happened a good place to start as usually if your computer is starting to get corroded at the connections you will start having odd drive ability issues etc. leading up to a no start condition.

 

Hi Luvmyxjs

Many Thanks for your very detailed reply, although She's never had a problem starting before and always first time on the button

But because this Car is almost like new, I have very seldom used her since I bought her some years ago, which could be one of the reasons that the Fuel Pump packed up

Though that has all been fixed now, with a Brand New Pump

You mentioned that it could be the Computer, not quite sure what you meant by that or where I can find it, so please could you tell me where that is, so I can check it out

My knowledge of these 6cyl Cars is Zero!

So any help you can give me would be appreciated

 

Computer, or ECU, is, in the USA, at the passengers side right footwell.

You need to remove at carpeted panel to access it.

You are in the UK....I doubt it would be moved....but I don't know for sure.

 

Hi Vee

Cheers!

I've already checked that one out but was wondering if 'Computer' referred to something underneath the dash

 

I was indeed referring to the ECU. I will just add again that most likely if you had no drive ability issues leading up to this no start you most likely will not find corrosion issues at the connectors to the ECU. I did not read on your response to my post if you know if the crank sensor has ever been replaced? Again mileage is not the only indicator why the crank sensor can fail. Appears that the magnets in the crank sensor can weaken over time regardless of miles and this is what happened on my low mileage 4.0L XJS. If you have not replaced your crank sensor since you have owned this car I highly recommend you go ahead and get that done first if for no other reason to get that off the possibility of causes for this no start and also as good insurance from a possible problem in the future.

I now carry a spare crank sensor in my car if that helps to convey how big of an issue this can be with the 4.0L. Good luck with getting this issue resolved.

Todd

 

Hi Todd

Sorry, forgot to mention the 'Crank Sensor' it's not been replaced as far as I know, so that may be the problem as you say

How easy is this to get to and replace?

 

Very very easy. It sits next to the crank pulley and is either one or two bolts that holds it on. easiest to get to from the underside so I suggest to jack the car up and get to it that way but it only sits in one position and once you have the car jacked up on "your" drivers front just takes a few minutes to switch over. Just be careful where it plugs in getting the connector apart so you dont brake the keeper on the connector off.

 

Hi Todd

I've tried everything else I can think of, so I'm hoping you're going to say 'I told you so'

BTW is the Crank Position Sensor on the Six, the same as the one on the V12

As if so then maybe I could try the one that I've got on my V12 Parts Car

 

I am sure they are not the same. They should however be the same on the '95 to '97 XJ6 4.0L with the AJ16 motor. This is what they look like and like I said I am positive it is the same part as the one used on the AJ16 XJ6 but you will want to confirm before you order. As you can see they are not that expensive so worth replacing as a starting point. The one I posted is listed on ebay in the USA but should be available also in the UK so just check on your EBay or through your trusted parts store It is one bolt that holds it in place and it reads the signal directly off the crank pulley.
https://www.ebay.com/p/Eurospare-Eng...5958773&chn=ps

Eurospare Engine Crankshaft Position Sensor Lhe1640aa Jaguar Xj6 XJR XJS

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Hi Todd

Many thanks for finding that Crank Sensor especially the Part Number which also checks out with a well known supplier of Jag parts in the UK

They can supply an Original OEM for around £50 inc delivery and vat

But first I want to get the old one off, so that I will know the way to put the New one back on

I've also followed 'Greg's' suggestion of Cleaning the Plugs on the ECU, which could have been the cause of the 'No Start' problem and so at least I can eliminate that one from the mix

I am also getting a good high pressure flow of Fuel, travelling through the Fuel Rail from one end to the other, so having tried almost everything, its looking like the 'Crank Sensor' as you have suggested

But what about the other one on the back of the engine

What does that one do? or is it only likely to be the one on the 'Front'

 

not sure which one you are talking about at the other end of the engine. Can you post a picture of it so we can see which one you are talking about?

 

Hi 'my bad' I thought there were 2 for some reason