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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15311
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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X type: intermittent..gauge..the fuel rail and there is fuel pressure

Customer Question

i have a 02 x type it has a reoccurring p0193 code and it has an intermittent no start when hot. i have a gauge on the fuel rail and there is fuel pressure when the problem occurs. i checked crankshaft sensor signal with a scope and it's ok as well. customer says he has replaced the fuel pressure sensor in the past. one thing i noticed is that the fuel pressure usually stays between 40 and 55 psi but sometimes it jumps as high as 80 psi. i also looked at fuel presssure with a scan tool and it reads correct.
Submitted: 5 years ago.
Category: Jaguar
Expert:  Richard replied 5 years ago.

Hello and welcome to


That fault code P0193 is for the sensor reading high voltage/pressure which makes sense since it did go all the way up to 80 psi. The fuel pump is controlled by the driver module located under the driver rear seat cushion. The driver module receives the signal from the ECM and controls both the power and ground side. I do not think this is the cause of the crank no start since pressure was present. When the engine did not start was it cranking strong, did you have spark and did you try jumping or boosting the battery?

Customer: replied 5 years ago.
i had a battery charger on it while running all the tests. it cranks normal. i also have spark when it acts up. i don't know about injector pulse because the injectors are underneath the manifold and i can't get to the connector. i was speculating that the high fuel pressure could cause the engine to flood and not start. i have another x type that i can swap known good parts to rule out possibilites. the pcm will be hard to do because of the anti theft system.
Expert:  Richard replied 5 years ago.
Yes we will not be able to swap the ECM without a Jag factory tool. CHecking injector pulse is not easy but you can go to the fuel rail connector which is clipped on the driver side of the intake. You can splice into those wires for testing purposes. The reason I ask about a charger is because I have seen low battery voltage cause intermittent crank no starts. The other possibility is the fuel pump even though we have good pressure we may not have enough volume. When the engine will not start remove the small plastic hose off the intake tube and spray some carb cleaner into the tube to see if the engine will run on the spray. This will tell us if we definitely have a fuel delivery problem.
Customer: replied 5 years ago.
I'm gonna tackle this job on monday i'm gonna wait until i get this car sorted out to accept the answer. I thought that this service was going to be like a step by step diagnostic walkthrough. I'm gonna try swapping some parts and i'll ask for you opinion on the results. I'm sorry if this taking a while i had to put the jaguar aside and work on other vehicles, i'll contact you again when i get back to work on this jag
Expert:  Richard replied 5 years ago.
I recommend we double check fuel pressure and volume. ALso spray some carb cleaner into the air intake to see if the engine will start and run on the spray. If it does then we know it is a fuel delivery problem. We can check power and ground to the pump at the fuel tank connector under the rear seat. Put your voltmeter leads to the thick red and yellow wires on that tank connector.
Customer: replied 5 years ago.
ok so i finally got around to messing with this car again. i had a hard time getting it to act up again but i think i may have found something. whenver it didnt start the fuel pressure jumped to 200 psi which is the reason the p0193 comes back. 1st time it acted up i relived the fuel line pressure and the car started right up. whenever it didnt start, the cart somewhat sputtered a little bit like a carburated car does when it is flooded. i belive now i have somewhere to look for the problem. is the fuel pump controller solely responsible for fuel pump output or should i look somewhere else? also is the fuel pump controller separate from the pump or is it serviced as a unit? i'm sorry this is taking so long but just bear with me
Expert:  Richard replied 5 years ago.
Basically the ECM signals the fuel pump module to activate the pump. It is the module that will duty cycle the pump by pulsing both the power and ground. The fuel pump module is located under the driver rear seat cushion and can be replaced. We can check the duty cycle with a scope or meter on the white and brown wires at this module.
Customer: replied 5 years ago.
I finally have this one figured out! after fighting with this car for 2 weeks it finally threw me a p0335 code (crank sensor). i did a search on iatn and i found an article where all did was replace the battery. I did not think this as a possibility because the battery was 12.6v fully charged and it passed a load test. boy was i wrong. i thought the p0335 was kinda strange because i replaced the crank sensor and the signal looked ok on the scope when it was acting up. i replaced the fuel rail pressure sensor and it made the p0193 go away but i was still stuck with the no start. i was barking up the wrong tree this whole time. battery fixed it. i hope this helps you with other customers.
Expert:  Richard replied 5 years ago.

Yes I have run into this before but we did not discuss that P0335. See my post on another question from two years ago.



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Customer: replied 5 years ago.
that p 0335 didn't show up until this morning. i struggled with this one for a while but the next one that comes in it will take me 5 minutes to diagnose. it's really strange how some cars react to low voltage.
Expert:  Richard replied 5 years ago.
Ok that is strange but yeah these vehicles do not like a spike in voltage. Glad to see you got it back up and running.

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