Greetings all . I have a 2003 XK8 , I've had it for about two years now . The gentleman that sold me the car said it had a fuel pump issue . He explained to me that , to start the car I had to prime the fuel line by turning the key 3 to 5 times before trying to start it . He said the pump in these cars are prone to start leaking around a "diaphragm" on the pump causing the fuel , in the line to leak down I figured cool , I'll just throw a fuel pump on there and she'll be good to go . Little did I know that fuel pumps for these baby's can run $500 and up , not to mention the install , I heard , could be a real pita . Not out of my range mind you , but I decide to put the job off until later opting to just "turn the key" for awhile . Two or three turns and she would fire right up in warm weather , maybe two or three more extra turns in the cold . After sitting with the engine off (warm engine) for a few minutes like in the 7-11 and out , she would start right up on the first turn , no "priming" needed , but after sitting all night , or not driving it for a day , I would have to turn the key to "prime" the line 5 or 6 times , and even more in the cold weather .

Naturally this process got old and quite embarrassing at times , so , I finally bought a new fuel pump , and immediately placed it on a shelf in my garage . Fast forward a month or so later . I had to take my wife to a meeting that lasted an hour and a half , about an hour longer than it was supposed to be . I sat in the car and listened to the stereo . 30 minutes into my sit I decided to start the car for a couple minutes to give the battery a little charge . I let it run for about two minutes and turned it off . 30 minutes later I did the same thing . 30 minutes after that my wife came to the car , I turned the key twice before starting , then I turned it over and it started like normal , two seconds later it sputtered and shut down , and would not restart . I wouldn't even try , just turned over and over with no indication of spark or rather , combustion . It just turned over until I almost drained the battery. I had to town it home . Laughing as I walked by my new fuel pump still sitting on the shelf .

The next day I'm in the trunk getting that fuel pump in . It was really not as bad as some of the reviews made it sound . After all was said and done , she still wouldn't start . So I did a little research and leaned of the procedure to use after flooding . I tried this off and on for several hours with my battery charger to assist , but still no luck . I pulled the air breathe tube from the throttle body and propped open the throttle plate to look inside the intake plenum , it had like two inches of fuel in the plenum . I used a hand held pump to remove as much fuel as possible and restart procedure (foot to the floor for fuel cutoff ) but still no luck . I looked in the plenum again and it had filled back up with fuel . I used a hand pump again to remove all the fuel I could . Then I pulled the plugs and poured about a capful or so of oil (oil quart cap) into the cylinders . Then I restated the procedure , but this time I disconnected the wire harness from the fuel pump to make sure no more fuel would be delivered . After two or three tries she started making combustion and was trying to start . Eventually the engine did start and run but only if I didn't touch the peddle , as soon as I touch the peddle she stutters and shuts off . when its running its very rough , rpm gauge fluctuating up and down and there are fumes or fuel vapors that burn your eyes . It did stop smoking but the idle will not smooth out , its just barely running , and it will continue running the whole time the fuel pump harness is disconnected , but if I connect the fuel pump harness it stutters for a second and just shuts off , just like it does if I touch the peddle at all , and the intake plenum keeps loading up with near two inches of fuel . Testing the schrader valve on the fuel rail drizzles just a few drop of fuel .

As you can see , this one has me puzzled . So I bring this to you learned gentleman . Any advise would be greatly appreciated .

 

If it idles and dies when you touch the throttle, probably lean.

I had a TB go bad and cause no start/fuel vapors.

I also replaced the fuel pump. BTW I paid $68 for a Delphi pump. That was 5 years ago.

Any codes?

 

No sir , no codes , just an intermittent check engine light that comes and go's every few months . Just to clarify , the engine will start and barely idle if the wire harness from the fuel pump is disconnected . As soon as I connect the harness to the pump it shuts off , just like it does if I touch the peddle . When the fuel pump wires are connected it will start up an immediately shut of , just like it did right before I towed it home . The intake keeps filling up with gas and I cant imagine this would be normal . I'm hand pumping out a pint or more of gas out of the intake after trying to start it . Very peculiar .

 

If I understand, it is now running off of the leftover fuel in the intake, it's not really running. You might want to find a way to let all that fuel evaporate somehow. There is a metal plate that seals off the intake in front, by the thermostat outlet pipe. See if you can easily remove it for venting. The top engine plastic cover has to come off.

Check the oil for fuel contamination, too. With the PCV, fuel fumes might come back in the intake and make it even richer.

Do you remember what code the car was throwing? Any of the P019x?

Get a cheap ELM327 (eBay/Amazon) and read the fuel pressure. The sensor is at the end of the rail, passenger side. Check the harness and vacuum line. Should read 55psi pretty consistently. Check that if you turn the ignition on (fuel pressure is on), but engine off, that there is not fuel leaking in the intake (injector stuck open).

Remember, this is a return-less fuel pump. The pump supplies fuel pressure to the rail, as per the sensor. All the regulation/bleeding is done in the tank. My superficial understanding is that there was a batch of bad pumps sold a few years back that had that regulation not perform as expected. The pump was fine, but the associated regulation was not, and fuel pressure was not held/maintained as specified.

 

I think the 03 system is a non-return system that relies on a pressure sensor that controls the fuel pressure by controlling the single pump. The 4.2 system is when the change over happened, if you have a 4.0, you have a return system with different controls. If this pressure valve is failing, it could cause the over-pressure that would fill the plenum with fuel by spraying more fuel than the injectors were designed to release under a given pulse width. It is inconsistent that the Schrader valve just dribbles though, if there is over-pressure, it should spray strongly. There are two other possibilities, one is that the ECM is misdirecting fuel flow,and the other is that you may have some leaking injectors. This is a job for a pretty good tech with a computer to track. If I was having this problem, I would replace the pressure sensor first.

 

The OP said no codes, which would be odd. What's the battery voltage?

The only time I saw fuel in the TB was when some electronic component on the TB went bad, but that threw a code.

 

Excellent information gentlemen and Thank You for your time and consideration .

Yes, it is a 4.2 . There were no P019x codes displayed although it did report a "Restricted Performance" when the harness was unplugged from the pump . Its now come to my attention that the low pressure at the rail valve , was when the pump harness was disconnected ;-) With the pump connected it has a good flow at the valve but what the pressure is I don't know yet . Sorry for that confusion .

The oil absolutely reeked of gas and was changed immediately . It will be changing again when this is all sorted out .

Harness looks good , clean , insulation is intact , vacuum lines are supple , not dry or cracked , but the pressure sensor is still a consideration .

I don't yet have an absolute reading on the battery voltage but I can tell you its strong , stays on a 2amp trickle when I'm away , 10amp charge when I'm in the garage and 50amp starter when I turn her over .

fmertz "Check that if you turn the ignition on (fuel pressure is on), but engine off, that there is not fuel leaking in the intake (injector stuck open)."

This is a big question I had . When I turn the key to the on position without turning the engine over , do the injectors spray fuel into the plenum or , does it just pressurize the fuel line ? Unless I have leaky or stuck injector ? And that functionally , no fuel should be introduced into the intake plenum until the engine is turned over ? I'm sure there was probably an easier way of phrasing my question but I'll just go with that ;-)

fmerts , great question and I'll have an answer by tomorrow . I hope to get a scanner on it in the next few days . I'm really starting to lean in the direction of an injector issue . Is there any chance that a faulty "Fuel Pump Driver Module" would cause the flooding symptoms I'm describing ?

 

The only way for fuel to get into the intake is for the injectors to put it there. They are controlled by the ECM. If it is calling for a pulse, the injector will open for the specified time and then shut. If the ECM is compromised in this area, it could hold an injector open and flood things with fuel. I would get the ECM on the Jag computer to see what's going on. If this checks out, you have an injector sticking open which is very possible. The trick is to find which one. Some shops have testers for injectors. Don't try pulling an injector and turning on the ignition to watch it unless you want to chance a big fire. If there is no one who can test the injectors, send them to an injector service shop for testing and matching. The car will run better if they are matched anyway.

 

I had an injector experience with my 96 XJ6. It was misfiring at idle with no codes. I sent the injectors in and the shop found that one injector was sticking at low pulse width (idle). Very unusual, saved me a lot of searching though. Sort of the opposite of your problem.

 

The injectors should only release fuel when the engine is running. Ignition on/engine off should pressurize the rail, but release no fuel.

If you somehow manage to get the engine running, you can use a cheap mechanics stethoscope and put the probe on each injector. You will hear a clear pulse from a working injector and should be pretty obvious if there is one that does not behave the same way.

 

My canned response after having a similar mishap is for you (Digital Dave) to check the nut(s) holding the ground wires from the negative terminal of the battery to the trunk wall. I know that I'm getting repetitive with this response but it's a simple thing and a loose wire will cause the same or similar symptoms to those that you have experienced.

 

Yes Sir Mr. Graphics , I did check the ground wire after reading your post on a similar thread , wire is tight and appears to be in perfect condition .

This is what I've learned so far ….

Turning the key to the ON position without turning the engine over does NOT introduce fuel into the plenum , no matter how many times I repeat this process .

Turning the key to the ON position without turning the engine over does not produce any pressure at the fuel rail schrader valve , not even a dribble .

Turning the engine over does produce pressure at the rail valve , enough to spray about a 4 or 5 inch stream from the valve .

Turning the engine over with the peddle to the floor does not introduce fuel into the plenum , but , the engine starts up with a high rev (rpm) and immediately shuts down as though I turned the key off at the top of the rev , before then engine can get to an idle rpm . After this process there is no fuel buildup in the plenum .

Turning the engine over normally , without touching the peddle , attempts to start the engine but only as long as the starter is engaged , release the key from the starting position and the engine dies . After this process the plenum is filled with fuel and no other attempts to start the engine will produce combustion …. unless , I disconnect the fuel pump harness , then , oddly enough , then engine will start and idle like its running on 3 cylinders . I let it run for about 5 minutes like this and it wouldn't shut off from lack of fuel , however , the engine would immediately shut off if I reconnect the harness to the pump , or touch the peddle in the slightest . After this process the plenum is always full of fuel .


When the plenum fills up , I use a generic hand held "break line bleeder pump" to empty it . It fills the little fluid cup between 6 to 12 times depending on how many starting attempts I've tried .

I haven't been able to find much information about the "Fuel Pump Driver Module" . Could a fault in this module be creating these symptoms ?

Again , I am extremely grateful for your time and advise .

 

My son works at an auto repair shop and he brought me this dandy little item today . Heading out to do a scan now . He has to take it back tomorrow so I'll have it done tonight . This thing probably cost more than I paid for the car , lol .

 

Current codes displayed :

P0193 - "fuel rail pressure sensor circuit high input"

P1582 - "flight recorder data is stored"

 

At this point, you need to read the fuel pressure from the sensor to get a sense if the sensor is working. They are about $50, so maybe you want to just replace it. The other scenario is that the sensor is fine but runs out of range because the fuel pressure regulation is broken and the pressure spikes. Another option is to get a cheap fuel pressure gauge kit (Harbor Freight?) with the right adapter and get a real reading off the rail.

This is a weird problem. It is almost as if there is an extra supply of fuel in the intake besides the injectors. FWIW, I replaced my fuel pressure sensor because it was leaking (as in the body of the sensor was leaking). Maybe yours is leaking too, and back filling the intake through the vacuum line. Maybe remove the vacuum line and pressurize the rail (be ready to catch fuel off the sensor in the off chance it is leaking). Just a wild guess...

Others have reported issues with the fuel rail dampeners leaking fuel, but I believe it leaks outside (and smells). I have not worked with this enough to know if it could somehow leak inside the intake under the right circumstances.

 

Since I am a Jaguar newb , I want to go ahead and post this picture to make sure I'm following you correctly . This is the sensor your speaking of ? and there should be NO fuel coming from the vacuum port , into the vacuum line ?

If this is correct then You may have found the problem . There is a very high pressure fuel stream coming from this sensors vacuum port , I would say more than double the pressure found at the rail valve .

 

Looks right to me, sensor at the end of the fuel rail, passenger side, under that big plastic cover. From what you are describing, the sensor leaks into the vacuum port. and is the source of your problems. You can try to open it (look like the body has snaps) to see if you can fix it, but I would just go ahead and replace it at this point. Raw fuel around hot engine parts is not your friend.

Best of luck, keep us posted.

 

Yes , you Sir are a genius , a Jaguar Genius , a JG ;-)

Thank you fmerts for figuring this problem out for me . You have saved me hundreds . Thank you all again for your time and advise .

I ordered the part online , it should be here in a few days . I will update my post with the results as soon as its installed .

Out of curiosity I decided to go ahead and open the sensor to see what I could see . Sure enough , inside the sensor casting just under the vacuum port is a tiny little cylinder that had a clear rubber like membrane over it . the membrane was torn and gas poured out .

Her is what it looked like after removing the remainder of the damaged membrane .

 

Glad I was able to help out, but I also feel you did your part. You came here seeking help the right way. You asked questions, you managed to get codes, you posted pictures, you followed up, and you bothered to post about the outcome, therefore helping others down the road. Glad to see one of these wonderful cars back on the road. I guarantee you that $50 part will feel like a $1M once the car runs again the right way.

Best of luck, keep us posted.

 

Sensor came today , put it on , fired it up and she's purring like a kitten . Thanks again Fred ;-)