Decided to start a new thread on my new to me Jag problems. I want to focus on this first because It's really not drivable this way. In my other thread about readers I mentioned that the check engine light is on and has the code P0191. I changed the fuel filter and there is no change. Although I did notice that when I went to relieve the fuel pressure there no fuel came out when I pressed on the shrader valve. I am reading 50 PSI when engine starts. It will drop to the 20s if I step on the accelerator quickly but it will maintain the 50 PSI after revved. When starting you can see while it cranks the pressure slowly builds to about 20 then the engine starts and pressure goes to 47 - 50. The on board test section tells me this:$07 EVAP SYSTEM LEAK DETECTED (GROSS LEAK) 395.8 KPA
Fuel pressure basically goes to 0 as soon as ignition is turned off.....
So any Ideas what to do next

 

The 2003+ cars use a single ended fuel system that varies the speed of the pump to maintain a constant fuel pressure depending on load. It should be holding a 55psi DIFFERENTIAL to the manifold, so your external gauge will show somewhat varying values depending on the manifold vacuum. Between idle and throttle full open, you should see between 50 and 55psi on an external gauge.

P0191 is pointing you toward the fuel pressure sensor or the signal to the ECU. The pressure sender is on the right hand fuel rail, near the front, facing strait up. There is a 3 wire connection to it and also a vacuum hose running to the manifold. Usually this code means the ECU got some nonsense reading like ground or +5 or a value that stayed the same even when the ECU changed the pump speed.

If your reader can show live data, try using it to read the fuel pressure and compare to the gauge. The two readings should be pretty close to each other. If the measurement is jumping around on the electronic sensor then you could try cleaning the connector. If that doesn't help then the sensor could be bad, but fortunately they are not too expensive nor difficult to change.

If they do always read the same then it's on to something else in the fuel system...

 

Charlie has you on the right path. I had the same symptoms as you with my original fuel pump, where the car ran ok unless I stepped hard on the gas. Fuel pressure was ok at idle, but when pressing down hard on throttle then fuel pressure would drop. I never had any codes though. I suppose your code could indicate a leak in the fuel system, but I would think that if the leak was bad enough to cause these symptoms then you would have serious fuel smell and obvious fuel leaks. So, I am guessing you might have two issues, a canister or evap malfunction, and bad fuel pump, although, I guess it might be possible that a lose or broken fuel line in the fuel tank might cause the code and pressure loss without dripping fuel or fumes. See my thread for the complete story https://www.jaguarforums.com/forum/x...l-pumps-78107/

Also, search for Reverend Sam's post on his fuel pump issue with broken plastic tabs, may shed some light.

 

There are no external fuel leaks....I just can't believe I drove it 300 miles and all was well. I did hit some rough spots in the highway toward the end of my journey because there were clumps of ice I could not see and thus avoid. The lack of any fuel pressure right after I turn off the engine makes me think something cracked on the fuel pump or other component in the tank. This is yet another incident in my life that helps me believe in a higher power ie guardian angel watching over me until I got home. On a positive point I got a look at the underside and the only dirt looks to have been deposited on my journey back. It's incredibly clean and obviously was a fir weather driver......I'm talking car show clean.

Peace!!!

 

You shouldn't expect the fuel system to hold pressure when you shut the engine off. There is a check valve in the pump assembly, but its intended to keep the fuel from draining back to the tank more than hold pressure. But what you should see is the pressure come up when you switch the key on before starting the engine.

A while ago I noticed that the pump was sensitive to the battery voltage and that the car would not only crank faster but would prime the fuel system better when switching the key on once I replaced the battery with a new AGM style. It basically cured a long start problem I had.

Might your battery be old? Or did the car sit for a while before you got it? A good long drive to charge the system up might well have cured your problem.

These cars do not like to sit and are very finicky about battery health and voltage.

 

Check the vacuum hose, especially where it connects to the manifold. Lots of heat there and cracks or loose fitment will cause problems. Replace it just for peace of mind.

 

I love you guys!!!

 

I read thru all of the bad fuel pump thread and am pretty well convinced that its the fuel pump since my car exhibits all of the symptoms that Steve describes. I am going to purchase a fuel pressure gage just to confirm that the pressure drops to zero immediately when the engine is stopped. I think the low pressure code pops up while starting the engine since it takes so long. I've cleared it while the engine is running and it stays off until trying to start the engine again. There were no engine codes when I picked the car up so I'm reasonably sur this was not a pre existing prob.

 

That code requires that the problem happen twice in two starts for it to set the CEL.

If you have a reader that can show you pending codes you might see it, but if you clear it while the car is running you definitely won't see a light again without shutting off and restarting.

When my pump failed I never got that pressure sensor code. Maybe Steve can comment whether he did.

 

I never received an error and never understood why. As far as I know, this is the first mention by anyone on the forum of a code being set with this issue.

 

Well I have been very ill since Christmas but felt good enough new years eve to go out and purchase a fuel pressure gage. I have been too sick since to mess with anything. Just before Christmas I added 5 gal of premium to the tank since it was sitting on about 1/4. It was still hard starting. Went to the garage today just to sit in her......cranked her over and started immediately. let it sit awhile and still started great. I'm not jumping up and down yet but is it possible that some gunk got in the check valve and finally lodged free???? still need to put the gage on......

 

Its vital that you keep fuel pressure in the system after you turn the engine off, at least for 1 or 2 hours.

If not and the engine is warm, the fuel will in the fuel rail starts to boil, which will cause a hard start. Pressure in the system will prevent this from happening.

I guess the last time you started the car, it was not run until full operating power, so not enough heat in the engine to have the fuel boil. This is why you now could start her immediately.

You need to fix the fuel pressure (probably the valve in the pump assembly, but that needs to be investigated).

 

Yes it will be awhile now ... I live in the Midwest us and there's about 2 feet of snow piled in front of the garage door...............

 

I put the analog gauge on the fuel rail fitting today. It showed a max of 40 PSI and would go down to 20 PSI occasionally. I was too lazy to go up and get my laptop to compare what the computer was saying. When turning on the ignition without cranking the engine I could see it go up to about 10 PSI and then drop immediately to 0. If I turn it on and off about 5 times the engine will start sort of normally. after the ignition is turned off when engine running the pressure immediately drops to O...........................

 

Local Mechanic quoted $1132.00 to replace the fuel pump (airtek). Just for giggles I'm going to have the Jag dealer quote it.........probably still do it myself.

 

That is about the going rate for a 2003+, and most of it is the cost of the pump assembly.

 

Yeah, The pump assy is stupid expensive. He's only charging 280 for labor. I'm suspecting I have the same problem sam had in the youtube video and can reuse my old pump. But if spring is coming around and I still don't have it fixed, then to the shop it goes........

 

Everyone has to make their own decisions regarding repair options and I can't sit here in my living room and say you should do "this", or "that". What I am happy to do is convey my experience and with hindsight reflect on my choices. I had the dealership do my repair, and for me, I am glad I did for several reasons. As you know if you read my saga, I had the original fuel pump replaced by the dealership, and within less than 1 year it was replaced either 5 or 6 more times (I don't remember the exact number, I would have to re-read my thread). I did not pay a cent for any of these subsequent replacements, and I was provided an XF as a free loaner with each service event. Each time the car was in the shop for this it was there for at least 5 days. Had I been without the loaner, or had to pay for a rental, it would have cost me quite a lot. Had I replaced the pump myself in my garage, I would have been really upset about doing it so many times. And had I used an independent mechanic, I have no doubt most would have lost patience with the situation and told me to go away. I don't mean to disparage independent garages, but there is a point at which they have to cut their losses. Additionally, I like to believe that Jaguar corporate took my concerns along with other similar issues from other customers and investigated the issue to find a solution. My service advisor and technician tell me they worked closely with Jaguar on this issue, and that Jaguar acknowledged a problem with the pumps. Hopefully they found the issue and developed a solution. I would think that when Jaguar dealerships run into repeated issues with replacement part like this, that Jaguar looks at them as opportunities to improve, and hopefully a design or process change had been implemented to correct these issues for future pumps. Who knows, maybe there were a lot of pumps sitting on the warehouse shelf for an extended time period and internally a rubber part hardened or disintegrated or a spring rusted, I don't know. But if something like that happened, maybe Jaguar changed an internal,process or part specification. My point is, I hope that with this forum my experience helped and helps others, but also, I hope that by using the dealership in this instance helps Jaguar be better, and in turn it helps others. Finally, as I said, had I not used the dealership, I believe in the long run I would have been out of pocket more money than I paid out initially. I know my situation was an anomaly and doesn't necessarily apply to all, but I also know others have had repeating issues with pumps, just not to this degree.

Lastly, I guess I am a little superstitious, as I cringe when writing this, but I still seem to be ok with my last pump assy. For at least. 7 months plus since the last replacement I was using ethanol free fuel exclusively, which for me isn't inconvenient to buy. However, when the summer humidity ended late fall (October/November time frame) I switch to normal pump fuel. The reason was that I began having an unusual amount of detonation pinging with the ethanol free fuel, which was only 89 octane. I don't know if there was a formulation change with the ethanol free I was using, or if there is a mechanical or electrical situation with my car causing the issue. I can say I have no codes, and no change in performance or anything. I am guessing there has been a change in the suppliers fuel, maybe lower octane. Anyhow, with the lower humidity I have been less concerned about the ethanol causing issues. But with the switch to premium pump gas now, I am using Briggs & Stratton fuel treatment, which is the only treatment I have found that was developed specifically to combat the problems caused by ethanol. Fuel Additive | Fuel Stabilizer | Briggs & Stratton
I don't have a commute for work, and so use the car relatively little. For example, I could have a tank of fuel last me 4-6 weeks or longer, so I believe "that", along with the high humidity of Florida may contribute to an ethanol related issue if indeed that was contributing to my problems. I have no idea if this additive is why I have not had a repeat problem since going back to pump gas, but it is cheap insurance in my opinion.

 

Yes, my next step was to have the dealer quote the repair. I have several fords and Lincoln's and have always had the dealer do the repairs. In Fact today the ford dealer repaired my drivers window motor, replaced tie rod end and sway bar bushings on my 94 Lincoln MK8. I always price parts with them because they give me a 25% discount and are frequently cheaper than a discount parts house.