I live in the beautiful riverside (Thames) town of Henley-on-Thames in the liddle ol UK! - On the Map it is approximately: 30 miles West of London and 30 miles South of Oxford!

Henley-on-Thames is famous for International Rowing via: Henley Royal Regatta, recently passed for this year sadly, because the ombiance at Regatta time is amazing, so too is the Pim's!

I have a 1990 Jaguar XJS V12 Convertible, nice condition generally, but having a few problems with it at the moment:


The car will not start, wont even fire, zilch!


Please Note: - The Ignition System is Marrelli


I have had the ECU tested and it is fine, we have a spark and fuel to the engine bay, (Sorry Chaps! - Under the Hood!) though neither have been tested for strength. The front Crankshaft Sensor has been renewed but not the rear. I have also been told by an Auto-Electrician that has had a quick look at it, there is no pulse to the Injectors!

Also, because I had a previous problem with starting the car when warm (even when berely started and stopped, to re-start again and later a complete fail to start situation, followed by running on one Bank only - a year ago, all plugs were replaced with new and one (Second Hand,) Amplifier. Broken Coil Connections were replaced and loose or fraid cables repaired or replaced, including a complete set of HT Leads - After this the car ran well until it was delivered to another garage for it's Annual Safety Test.

Once there, the car ran out of repaired petrol but fuel (Sorry, Gas!) was put in and eventually it was again started. It could not be tested for a few days, but while shunted from Garage to Yard and back, several times it did on occassion fail to start immediately or ran a bit rough when finally started. The Car was finally tested (which it past!) But on collection I found it was running, it apeard, only on one Bank!

After a few day's the vehicle was returned to the Test Centre Garage, who are not Jaguar Specialists, but given the so called Specialist Garage accepted 'No Resposibility' it was the only thing that could be done!

The Test Centre Garage has been most helpful and carried out the work stated in the original parragraph above but to no avail!

To re-cap:

Despite previous works carried out and parts replaced that apeared to cure a previous start and running problem's..........

There is an (unqualified) Spark and Fuel Pressure, the ECU test's were normal but there is said to be No Pulse to the Injectors and the front Crankshaft Sensor has been replaced!


I'm trying you guys across the pond because I am getting nowhere here, yet, not only do you seem to know what you are talking about and are, it seems, much more willing to help!


HELP Please!: ASAP!!!!!!!!!!!!!!!!


Thank you,


Raymond

 

Off hand I can't remember the difference between the front and rear crank sensors but I'd be tempted to replace the rear one as well. But that's just a wild stab.

The issue of spark and injector pulse must be verified one way or another. The spark must me strong and blue...easy test...strictly a visual thing. As for injector pulse simply use a noid light to see if the injecotrs circuits are working. If the circuits are OK but there's no clicking from each injector I'd suspect a faulty injector.....but not a slew of simultaneously faulty injectors

Have the coolant temp sensors (one for the fuel injection ECU and one for the Marelli ECU) checked. If they are "open circuit" or the connectors are faulty, the engine won't start.

If you have blue spark, 12 working injectors circuits, and good temp sensors I'd next check fuel pressure...as the mere presence of fuel isn't conclusive

Cheers
DD

 

I admit it possibly would have been a good idea to replace the temperature sensor given the original problem, but they didn't for some strange reason.

I will do the checks you suggest and see what happens. do you or anyone else out there know of any obvious reason why there would be no pulse to any of the injectors if the ECU checks out, as it does?

Many thanks, will be back,

Best Wishes, Ray

M

 

Doug,

Have just re-read your last reply and noticed you talk about the Tempurature Sensor for the 'Marelli ECU' - I had know idea there is such a Beast, can you tell me where on the car that is? Or is that as miss-quote for something else,

Best wishes,

Ray

 

It might seem too simple but have you checked the inertia switch, this supplies power to the fuel pump relay.

The coolant Temp sensor is on the front of the A bank coolant rail also the air intake temp sensor this is located in the A bank air filter.

There is also a fuel temperature switch under the RH fuel rail this is to increase fuel pressure for hot starting.

The rear crank sensor is engine speed and one of its functions is for cold start. Under 350rpm the ignition timing is dependent on engine RPM air intake temp and throttle position. Ignition timing timing moves from crank to run at 350rpm

cheers
Warren

 

Right side water rail, just aft of the thermostat but ahead of the sending unit for the dashboard gauge. It looks physically the same as the coolant temp sensor for the fuel injection which is in a similar location of the left water rail.

Cheers
DD

 

Maybe they tested it and found it to be OK.







All of the injectors are wired through a ballast pack. It might be faulty....a bit rare...or have a poor connection....which isn't rare :-)





ECU failures are somewhat rare so this is probably academic, but how did the shop test the ECU?


Cheers
DD

 

Hi Doug and all that have helped me! - Here is an Update:

I have now fitted a new Battery to the Car as the old one no longer seemed to be Holding a Charge!

I have fitted no more new parts other than the above as yet.

I am now able however, via pumping the excellerator many times, getting the engine to fire and try to start but that is as far as it goes without starting the process all over!

The Car trys to start most everytime I do this!

I have now taken off the fuel filter and blown it through with a high pressure Air-Line and have also put a Gallon of Fresh fuel in to the Tank - But Still No Getting beyond the latest Status Quo!

Otherwise, the Car has been cleaned and is looking really great but nice as it looks I still cannot get it running - but do you and/or anybody else have any more words of wisdom that may help - please!

 

IS NOBODY TALKING TO ME ANYMORE!!!!!

I have just purchase another Crank Sensor for the rear of the engine, known as the Speed Sensor. This sensor I am told, is identicle to the TDC Sensor on the front of the engine and therefore carries the same part number, the TDC sensor on my car has already been replaced. I have been told to replace this because we have now discovered, the fuel pump, although runs for a few seconds at ignition on, does not restart and run during cranking!

The problem I have now is how to get to replace this sensor, which I understand fits into the Bell Housing. Does this fit on the underside of the Bell Housing, can it be got at from the underside of the car or is it on the top or side in which case, can it be reached from inside the car somehow?

Please help and please help quickly, am starting to get withdrawals from being unable to drive my car!

Regards,

Ray

 

The rear crank sensor is (fairly) easily replaced from below....you'll see it.

Cheers
DD

 

If replacing the rear crank sensor does not solve this problem try grounding the orange wire at the fuel pump relay. The pump should then run whenever the key is "on"....not a desirable arrangment but it may help you in your diagnostic process.

Cheers
DD

 

Many thanks Guy's, will heed all you say and report back - I seems so hard to find diagrams on these things!

While on, guess what I have found here in Henley-on-Thames, UK! - An in- tact, though a little sad looking now, XJR's Coupe, just begging for renovation! - It's from the Jaguar Racing Model Line that ran from the Tom Walkinshaw British Racing Team Series of Cars- Think it could be bought cheap, interested anyone? - Lol

 

Hi, i am new to forum and have same problem. Started out as dead A bank, replaced cap and rotor now no start, won't even try. Did you fix your problem? Any other ideas appreciated. Thanks.

 

Jagvirgin,

It would be better to start your own thread rather than get mixed up in this one.
Give as many details as you can about your car and problem, it will help anyone trying to give advice.

 

I have now replaced the rear crank sensor but problem stil existing. Symptoms have been isolated at the moment, to the Fuel Pump not running during cranking. So if anyone knows the reason for this, that is not either of the crank sensors then please suggest! - Have someone to call first to ask, but believe next stop may be Pump Relay!

 

Have you tried Doug's relay bypass idea?

 

No, what is it?

 

Here you go.

 

Thanks Nori/Douglas,

Think I will just get a new pump relay anyway, not that expensive. Been a bit distrated recently by EBay disposals but back on the case this week. Fuel Relay next cos it's cheap and easy and part of the process of elimination - But any other ideas as to why a pump doesn't run on cranking?

 

The fuel pump relay is grounded/earthed by the orange wire from the ECU. I think there's some history of that ECU function going dead....an internal problem with the ECU.

Also, the ECU needs to "know" that the engine is being cranked. I believe this comes from the starter relay which has, among others, two white/red wires. One goes to the starter and the other to the ECU.

The fuel pump relay also relies on a functioning "main" relay to operate, by the way.

Do you have a wiring diagram for the car? If not, you shoud !

Cheers
DD