Hello Jaguar forums. Last night I was driving home in my 06 STR on the freeway at about 70mph and about 10 minutes into the drive my car lost power in the span of about 15 seconds. By the time I got over, the car stalled and won't start now. It cranks and has no check engine codes. It sometimes starts and idles at 200ish rpm for about 2 seconds and then dies. I don't see any leaks, overheating coolant, bubbling coolant tank, smoke, or anything unusual. Is it common for fuel pumps to fail or anything on that base? I also have papers from the previous owner and one of them shows one coil was replaced which I know is not recommended. Any advice on where to start a diagnosis would be highly appreciated. The internal electronics seem to all still be working such as shifting into neutral, ignition switch, electronic E brake. Thanks

-Nick

 

Check fuel pressure. The S-Type R uses two fuel pumps.

Have a look at the wiring diagram and check the fuel pump relay in the rear junction box at position R15.

Here is a link to the wiring diagram:

JagRepair.com - Jaguar Repair Information Resource

What is the battery voltage across the terminals with the ignition in the OFF position after five minutes? It should be a minimum of 12.5 volts, if not, the battery would need to be replaced to have the correct voltage levels for further diagnosis.

 

Thank you for the quick reply. I am currently not at the car, but plan on doing that tonight. So I would pull off the relay and test the terminals with a multimeter? Also, what is the best way to check for fuel pressure? Does the STR have a fuel pressure tester hookup line in the engine bay? Thanks.

 

NB gave you great advice. I would purchase and install a fuel filter. Alot of owners neglect this little maintenance item.

It's pretty simple to replace. It's located behind the rear drivers side front tire behind the inner wheel well. There are videos here or on YouTube that show you exactly what to do.

Personally I would start there.

 

Check the impact switch. On 03-04 STRs the switch is on the left side of the driver's foot-well. I've had mine pop out on a steep incline and once hitting a bump. If the button is popped out push it back in and your car will start.

 

Checked the impact switch and seems to not be triggered. I plugged in the torque app and am getting 77psi fuel pressure and it drops a little when trying to start it.

 

That sounds too high - but I can't see why it would have caused a breakdown.

It might prevent starting (too rich). Maybe try WOT (see below acronyms) cranking (to clear the fuel out). If you can, have someone sniff the exhaust for petrol (gas) fumes. Don't do very long cranks (can overheat the starter motor).

 

Thanks for the kickdown info and signature instructions. Still no luck on it. Is there any security sensors or relays that can trigger the shut-off? I believe the battery is pretty new but I will probably test that next.

 

Agreed that sounds high, but am not sure of the specifications.

Before worrying about other possibilities, connect a mechanical pressure gauge to the test port on the fuel rail. Make sure what you're seeing there agrees with the value on your scanner, and that both are within specs.

 

Yeah, I'd prefer to do a physical fuel pressure test vs an obd2 test. Can someone point me to where the fuel rail plug for the tester is located on the STR? Would highly appreciate it.

 

Fuel pressure for the S-Type R should be 3 bar at idle and 5 bar at full throttle.

There is no longer a schraeder valve in the line so an adapter must be used that fits into the fuel line at the quick disconnect fitting to allow testing of the fuel pressure with a gauge. Refer to the Workshop Manual section 310-01 for the procedure.

 

I'd try another app just in case Torque has got it wrong but if not then it sounds so high that it may be the problem.

I'd like to hope the PCM would compensate but maybe it can't - or maybe the sensor is reporting wrongly i.e. is faulty. If that is so and the PCM does compensate it will be delivering too little fuel.

 

Could someone point me to the adapter such as a photo or link?

 

I had a 2005 STR and it did have the test port so I think you do to. Maybe the 2006 STR did away with it but you can check and see?

Look at this thread. I have a diagram in it and item #6 is the Schrader valve and my fuel pressure tested connected to it. The test port is on the passenger side at the back of the fuel rail.

https://www.jaguarforums.com/forum/s...s-power-77995/
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Here is an image of the adapter in situ from the Workshop Manual:

From the
Workshop Manual:
'Vehicles with supercharger
8. NOTE: Make sure the special tool is fully seated to the fuel pipe
connections.
Install the special tool.'

 

Awesome! Thanks for all the replies everyone. I'm going to try and hunt down a fuel pressure tester and quick disconnect line tools tomorrow and move forward from there.

 

Update. I never got around to finding the pressure test kit today. But in the meantime, I experimented with the fuel pressure sensor on the driver side rear of the fuel rail. I unplugged the sensor and started the car and it started right up. I only did it for a few seconds because I assume it's not good to run with an unplugged sensor. But the weird part is it ran and didn't stall. Would that mean I have a faulty fuel pressure sensor?

 

I think the PCM would substitute an estimate. Probably throw a code (but maybe not immediately as many need 2 trips).

I don't think it guarantees it's the sensor but it would now be my #1 suspect.

If you plug it back in does the car now run or stall or what?

 

Yeah I plugged it back in and it went back to not starting. Got a fuel pressure sensor code as expected. I decided to go for a new sensor and ordered one. Hopefully that moves towards the right direction.

 

Looks likely. Let us know as if it is then others can benefit - and if it isn't... more ideas needed!