Hi , I have a new to me XJR x350, It had a coolant leak. I was fixing it when I noticed the water temp sender was also leaking. So I ordered a new sender and installed it this morning. I went to drive the car an hour later and it cranks fine but no start. I had to disconnect the MAF/MAS? to gain access to the temp sender otherwise nothing else was touched. There is a connector right next to the temp sensor I think it is a knock sensor plug? So I checked over everything ran an OBD scan, no codes however it is not a Jag specific OBD code computer. I checked the battery it was 12.5 volts ( new 9/17) but just in case I put it on a charger for a few hours tested again 13.7 volts no change. Car ran great last night other then the aforementioned coolant leak no known problems. It was never overheated. So I am looking for advice on where to start. I read some other threads indicating battery, fuel pump fuses relays (Checked). I sprayed some starting fluid no change I think it is spark issue. Could the temp sensor cause a no start condition? I know Jags can be quirky I have experience with 98 XK* and several XJS's.

 

The MAF Sensor is Directional and the car will crank no start if it's in backwards with the plug facing outward away from the motor.

Also check ALL your Vacuum connections up front.

 

Had same issue, was the crank sensor. Located under car at engine bell housing. Local auto parts store has it for about $40.

 

Thanks for the replies, I checked the mag and wiring, seems ok. Also could not find any disconnected vacuum lines. I thought crank sensor but have had no signs of failure. Balackat did your sensor failure throw a code? No codes, but I have also ordered a icarsoft scanner. Do you know the ohm range for a good crank sensor? Thanks,George

 

No, mine did not throw a code. This car is not great at throwing codes especially misfires!

 

Thanks I'll have a look on Audi and Bmw the sensor has a resistance of 1000-3000 ohms but will usually work if out of range but when it's open ie broken coil will stop alltogether. Same with Jaguar?

 

I think it is possible that the coolant temperature sensor can cause a long crank, not sure about not starting at all.

 

Maybe put the old leaky one back on and see if it starts. Easy way to eliminate that as a problem.

 

Eric thanks , first thing I did was reinstall the old sensor no go. I am waiting for a crank sensor to arrive. In the meantime I received my icarsoft LR II scanner no codes with it either. I will post after I get the crank sensor. I have had to replace crank sensor on BMW and Audi previously. In both cases the degradation was gradual and with the Audi of you splashed cold water on it would allow the car to start. Since no other suggestions I decided to replace it as it is 15 years old but assuming its the same type of sensor , it appears to be from the pictures, wire coil with a magnet instant failure is seems unlikely. However given the list experience represented here seems as though it does happen. When I switched over from german cars I expected some additional trouble but seriously the XK8 I have worked on extensively never has had mysterious problems. XJS has but once they were sorted it has been an extremely reliable car. So I am hoping it will just be a hiccup in the road. Thanks, George

 

FYI, my crank sensor went out of the blue suddenly at an Auto Zone (local auto parts store) parking lot of all places.
I pulled into Auto Zone to patch a leaking throttle body coolant hose. Once done and ready to go the car would not start. Crank but no start. Used their battery booster, even had the battery checked. Had to tow the car and spent the night figuring it out. Ironically I went back ti Auto Zone to pick up the crank sensor.
Never had any issues starting or any tell tale signs of crank sensor being on its way out.

 

Hi all, well it is not the crank sensor. I noticed however when under the car there may still be a water leak form the back of the engine some where. Is this most likely form the water line running under the intake manifold? I have a new theory that as I stopped the leaks from the radiator hose and temp sensor maybe I made the leak some where else worse and it compromised a different sensor like camshaft still no codes. I am going to check the car over tomorrow more closely. Thanks for the help. George

 

If it were me, the first thing that I would have done was to put a digital meter across the battery, and monitor the voltage while the engine was cranking. Jaguars are extremely finicky while the engine is being cranked over as the battery voltage must remain above a certain threshold before they will ever start. I'm not exactly sure what that threshold may be, but it's set relatively high.

 

Good advise, a large voltage drop could well be the reason.

 

Can you measure fuel pressure with the I Carsoft?

If not check Scharder valve on fuel rail (if you have one).

 

+1 on checking fuel pressure before throwing any more parts at the car. If there is no fuel pressure, check the fuse and relay. If the fuse is good, swap the relay with another one of similar design to eliminate that as a possibility. If there is still no fuel pressure, the fuel pump is likely seized.

If the battery has been fully charged, it should show a minimum of 12.6 volts when measured with a voltmeter across the terminals. Do not rely on the OBD Bluetooth interface to tell you the charge level as the voltage at the terminals may be different from the OBD port..

 

Hi I had a chance to check the car more thoroughly battery tests as new. No fuel, I could not find the shrader valve do all XJR's have one? I did not have a chance to look at the fuel pumps, as I thought they were in the trunk like the XK what a relief to find out as I have to do is take out the seat. I checked all the fuses and changed relays no improvement. I looked up the pump information and there appears to be two pumps is it normal for both pumps to fail simultaneously? Obviously if I find power at the pump they are bad but what if there is no power at the pump which ECU or sensor tells the pumps to run? Many Thanks, George

 

Check inertia switch under dash, near front of drivers side door. Ensure it's not tripped and depressed in.

 

Hi all the inertia switch was not tripped and has continuity. I checked the pumps they have no power, I did not jumper them I did not have a suitable length of wire. I will get a piece of wire and try jumpering them to confirm operation. Do both pumps operate at the same time or is one for high demand situations? I looked in the service manual and it appears the REM controls the fuel pump. I saw some tests and fuses to check in the manual ( all fuses test good) but I could not find the wiring diagram. Is the wiring diagram a separate document? The service manual I have has a table of contents and five parts electrical being part 4 but no diagram. Also still no codes. It seems the REM can be replaced but then requires dealer coding? Anyone with experience with the REM? The car cranks normally so for now I am ruling out the PATS system, does this sound logical? After I found the no fuel condition I did not go further and test the ignition system. If I do and find no spark what could I be missing that the car is not getting the proper signal to operate? Key is operational or would not crank so receiver and transponder of the PATS system are working? I have two keys same with either key. At least I am making some progress. Thanks in advance, George

 

Here is a link to the MY2004 X350 Electrical Guide:

https://www.dropbox.com/s/96nxuowykn...Guide.pdf?dl=0

 

Verbryck

Sorry if I misled you about the Schrader valve. My Jag (late 2003) has one but I know

some others do not.

Re fuel pumps I have no direct experience with Jag fuel pumps (not yet!) but

I believe one pump keeps the tank level on both sides of the "saddle' and

they run on a PWM signal ie pulse width modulated hence if you apply 12v

then do it for only a short period.

I don't find the format of the Electrical guide very good. This one may be better

and it's 2006 on.

http://www.jagrepair.com/images/Elec...al%20Guide.pdf

Good luck