nice pic

 

Thank You, My dog and cat are extraordinary.....However, the car remains in the shop!

 

The saga continues....my car was towed home today, then they drove it into the garage, purr's like always. They replaced the fuel filter and tank again to verify they were working, as well as the relay. They replaced the fuel pressure regulator, it had been seeping, they also checked ground and ECM connections and still unable to solve the problem. The owner of the shop said it was the first car in 65 years that he was unable to fix. He said he thought there might be an issue with the ECM, but was unsure. I'm just, I don't know what to do? Anyone have any suggestions? The more I have researched this particular problem, the more I have found it happens in every make and model of automobile, what do they all have in common that would cause this? Thank you to all who have tried to help.......

 

Hi Julia,

So sorry you're still dealing with this hassle. I may have mentioned before that sometimes problems are caused by more than one contributing factor. I suspect your leaking Fuel Pressure Regulator was one contributor, but there must be one or more others.

In reviewing what you've told us so far, a couple of statements stand out:

1. Your mechanic has been operating under the assumption that the problem is heat related. That may or may not be true. If it is true, has he tested the Coolant Temperature Sensor as I suggested in my post #10? If I recall, the CTS resistance should vary from a few kilohms at ambient temperature to something closer to zero ohms at full engine operating temperature.

2. Has he tested the operation of the Oxygen sensor? Backprobing the signal wires, the voltage should swing between just under 5 Volts to just above O volts.

3. Your mecanic has stated that the only stored fault codes were "old" and "had nothing to do with the current problem." There is no way to tell on an XJ40 if a code is old or new, and based on your mechanic's lack of success in resolving the issue, it seems possible that he was not certain of the meaning of the codes that were read. Please ask him again to tell you the exact codes that were read and please report them here. In fact, now would be a good time to read the codes again using the VCM as described earlier - the kind of symptoms your car is experiencing have a high probability of triggering at least one fault code.

4. The strong smell of gas fumes could indicate a rich running condition. The leaking Fuel Pressure Regulator was contributing to that. There are only a handful other components associated with the Air-Fuel Ratio (AFR) or fuel mixture. The CTS and O2S are two of them. Aside from the ECM itself, the other components include the Intake Air Temperature Sensor (IATS), Mass Air Flow sensor (MAF), the Exhaust Gas Recirculation (EGR) system, and the Secondary Air Injection system (if so equipped). Also the carbon canister purge valve, which, if stuck open, allows fuel vapors from the fuel tank to be inhaled into the intake manifold via a port on the underside of the manifold behind the throttle body. Your mechanic could try pinching the rubber hose that leads from the carbon canister ahead of the front left wheel to the underside of the intake manifold to cut off any fumes that are being inhaled under improper engine operating conditions.

5. Has the mechanic checked the air intake plumbing for any obstructions, such as at the nozzle of the air filter housing that fits into the front left fender, inside the fender itself, the air filter and housing, the MAF sensor, or the pipes from the MAF to the throttle body?

6. I think you said the mechanic had ruled out catalytic converter obstruction - is that correct?

7. Something else just occurred to me. The location of various relays changed over the course of the XJ40 manufacturing run. On your '94, the fuel pump relay is located behind the right rear tail lamp. Is that the relay your mechanic has replaced, or some other relay? If they have consulted the electrical schematics for XJ40s prior to the '93/'94 model years, they may have replaced the wrong relay....

8. In your latest post you said the mechanic "replaced the fuel filter and tank again." Do you mean they replaced the fuel tank "again?" Surely they haven't replaced the fuel tank even once?

Cheers,

Don

 

Hi Don, sorry to take so long to get back with you......The car is back home in the garage, the owner of the shop towed it home and then drove it in the garage.......Anyway, yesterday, I went to the arm rest, removed the cassette holder, and followed the steps of having the key in the II position, then pulling the instrument fuse, looking for fault codes, nothing came up, however, I didn't understand why the tack and odometer would drop to zero when the ignition isn't on, in the II position, they are in the 0 position, perhaps I misunderstood. When the car is in the number II position, the one warning light you mentioned in your earlier post is on, along with the light out warning(never been able to figure out which bulb is burnt out) and then below the tack, the battery light is on. When the ignition is running those lights are no longer lite with the exception of the burnt out bulb warning, my oil light does come on when the car is first started, it takes a few minutes for it to go out, that is new since my last oil change. The car is tuned up, a new battery was installed in December with a quick disconnect because the battery was draining if the car wasn't driven for 6-7 days, that has been an issue since it's purchase in 1994. The only issue the car has been having is the A/C, the fan sometimes seems to run but no air comes out, then it sounds like its hesitating turning on and off, the mechanic says its the temperature control unit that needs to be replaced on the panel.
So, it continues, I sent your recent inquiry to the mechanic and asked if he could please reply to your questions and give me a detailed list of what he has ruled out. I will let you know as soon as I receive his answers.... Thank You once again, your help and attention have been invaluable to me. Cheers, Julia

 

Hi Julia,

With the key in position II but the engine not running, depress the VCM button on the trip computer on the small panel to the right of the steering wheel. If any fault codes are stored, one should show up on the dash below the speedometer. The fuse box in the center console only comes into play to read additional codes if you find that one is stored. If your battery has been disconnected, there may be no codes stored now.


Don't worry about warning lights that are on when the engine isn't running. Regarding the bulb out warning, check all your side marker lamps, fog lamps front and rear, reverse lamps and brake lamps (get help for those), and license plate lamps.

This is fairly common on an XJ40, but if it's a new issue on your car, perhaps the oil was changed to a modern thin multiviscosity oil such as 5W-40. Off the top of my head, I think for summer in most climates the Jaguar spec is 20W-50. The oil pressure sensor on these cars is a common cause of false low oil pressure readings.


I would recommend that you start a new thread on the A/C issues since there will be a lot to say and it will be better to have that topic covered in its own separate thread.

Please keep us informed!

Cheers,

Don

 

Hi All, the saga of my Jag that no one could fix has come to a happy ending......finally. I by happenstance happened upon a retired disabled mechanic who worked as a trainer and troubleshooter for Good Year and a man with knowledge and integrity........after 5 fuel pumps, relays, fuel filters, vapor hose checks and god knows what else.....the connection between the battery and the fuel pump, was faulty, it would show it was getting voltage, the car would start, the vibration of the car jiggled the wires enough that would cause the car to die, the plug was bad, the plug has been removed, wires soldered together and my car is now running like a top......a top cat! Thank you everyone! Julia

 

Happy ending!Glad to hear you're back on the road again!

best wishes

Larry

 

Julia,

Congratulations and thank you for reporting back so we can all learn from your experience.

Happy motoring!

Don

 

Thank you all very much.........you all were right to question the mechanic that failed to fix it, I can now safely adorn the mechanics jumpsuit, as assistant only, and aide in the replacing of a fuel pump and gas tank, small steps to help me not be taken advantage of again..............Happy driving