Does anyone have a part number for the valve in the photo? Is that even what it's refered to as? A "pressure release valve" ? Is it changeable?

Just to mention, and I'm super tempted, if anyone needs this fuel pump assembly it's 187£. Auto Reserve is a group I've bought from before and they are great. Jus say'n

I have an intermittent CEL high rail pressure. I believe p0193. I've replaced the sensor, am using techron FI cleaner now, have changed the filter and am wondering what my next steps should be? I think I have a sticking or fried valve - the one in the tank I've heard others talking about. Maybe?

The car sat for a GOOD while...
Is there a smart way to just clean this thing?

My fuel pressure according to the OBD reader will go up to 58.x or as low as 52.x there and around,,, and does like to and will find 55.x psi but it definitely doesn't HOLD there even while idling. Today I turned the engine off (CEL not on) and back to the ON position just to see what the sitting fuel rail pressure was after SHUT DOWN. It was at 70.1! And stayed there.

The next start of the car (doesn't happen 100% of the time) triggered the CEL,,, popped for the p0193.

If anyone has a part number or suggestion I'm all ears.

 

Is this thing called a fuel pressure damper?

 

You have correctly deduced that it’s purpose is to limit the maximum fuel pressure in the system.

Unfortunately it isn’t available as a separate part, at least not from Jaguar. Best hope would be to try to get the part numbers for the damper itself and source a replacement.

 

That's what I'll do. Thanks.
Or take a peak at this one and hopefully work to free it up.

 

My problem has gone from bad to worse. First, pressure too high,,, now, pressure too low. Here is the part, but for the life of me I can find it... I have a second part/valve (how I got it is a story) - first set of numbers is the same last four and 2 letters are different. What now?

Orings in the assembly look fine/good/perfect.

If someone can locate this bit,,, I'll have a sandwich delivered to your door - or, take out of your choice. Just a couple good driving weeks left, ya know!?

 

The fuel required by the engine management does not rely on the part you have in your hand.

The fuel pressure delivered to the injectors is control by varying the fuel pump via PWM. (Pulse Width Modulation)

It is a RETURLESS system and has no actual FPR (Fuel Pressure Regulator) like a fuel return system.

 

Hey Man...how goes it... What I understood was that this little gizmo sitting in top of the intank pump assembly "pops off" at about 60-70 psi (maybe less) holding a fuel pressure when car is off AND helping to regulate the pressure at about 55.3 when running. Give or take a pound or two while running...? No?

Now, when running, fuel just comes out of the top of this one. Fuel pressure goes way down - as seen via obd reading.

 

2003 MODEL YEAR XK
SERVICE TRAINING
TECHNICAL GUIDE
PUBLICATION PART No. T2003XK
DATE OF ISSUE 09/30/2002
© Jaguar Cars North America
PRINTED IN THE USA

Fuel Pump
To support the installation of the 4.2-liter engines and continuing the drive for fuel
consumption benefits, a new fuel system including fuel tank, fuel pump, pipes, breather
pipes has been installed.
The XK now benefits from the use of the return-less fuel delivery system very similar to the
X-Type and S-TYPE models.
One major change on supercharged (S/C) variants is the use of only one fuel pump instead
of the usual two as used on all previous S/C models (XJR, XKR and S-TYPE R).
The fuel pump uses the same principle of operation as the on the X-TYPE where the ECM
monitors differential pressure across the fuel injectors and the injector pulse width and
duration to accurately calculate the fuel quantity being delivered to the cylinders. It uses
this to demand a specific fuel flow rate, which it communicates to a fuel pump driver
module located in the right hand side rear wheel arch.
The ECM use a frequency of 150 Hz (PWM) signal during average conditions, varying its
duty cycle between 4 and 50% to control fuel delivery rate or turning it to 75% to turn off
the pump.

 

Got ya. I've read that article. Been thru heck and back with the fueling system in this car... Still, the question... What's the part with the red arrow DO?

 

If you've got fuel coming out of the top (how do you see that?) then it's stuck open/leaking

What you said above about opening at a specific pressure to release fuel back into the tank.

Don't know if you've seen this thread from Digital Dave in your travels:
https://www.jaguarforums.com/forum/x...9/#post2055340

A search on the numbers brings up nada. Only ones I could find that were remotely similar were on Aliexpress (4.0 bar, which is a tad low anyway) but someone's making them. Who is the pump OEM - Denso?

 

HellO, Michael. Good morning...

Yeah, I've had NO luck finding one. None. I got "close" using the first string of numbers leaving off the last 4 and the letters.

I read that thread and will go back and read again. I think the import bit I read in that thread, or another, is the procedure for placing the valve and making SURE the Oring is rightly captured at the bottom of it's housing. I will pay attention to that and NOT breaking tabs. It's 4 little tabs that need to be bent out of the way to remove the valve. All hair raising considering the cost of the assembly.

It's a VDO pump. I can see it leak because I'm one ah them rebels that cut a access hole in the back deck. And I'm thankful for that today. During the 2sec prime, once I made it home, I could see (not clearly due to the orientation of the pump in the tank, the angle even when jamming my big head into the back dash area) fuel spurting and spraying. Short tests. But, with a couple key turns the pump gets close (or tries) to achieve right pressure. On OBD, pressure rises and immediately falls.

With OBD, when I turn off the key, pressure drops to zero or close. When driving there is a direct relationship between the gas peddle, revs and watching the pressure rise and fall. Go up a hill (which I unfortunately did yesterday, got caught on the road with this problem) and it's like she is running out of gas. No fun.

I have a second valve I will try. Came out of a gift package sent by a member when I was struggling with fueling early on. Turned out to be a faulty inertia switch whose internals were corrupted in the "flood"...

Onwards. Got to solve this. It's solvable. Then,,, the dreaded NO START with key turn. Although the trigger is working just fine, I wanna be rid of it...

Thanks

 

The whole thing will jus drive ya nutts, lol...
They LOOK alike... But as we know, that ain't enough!

 

So. Things are better, certainly better than what I had last run, and I learned why. Sheared Oring...

As I learned from another members thread,,, I placed the Oring IN it's housing on the plastic/assembly side and then pressed in the valve. Grease or oil on the ring and valve stem to stop binding... On removing the valve, I used a screwdriver to BARELY get the tabs to clear the valve edge on ONE side. Then, to hold up the valve while doing the other side, I ran a small screw driver shaft, skinny allen key or something between the underside of the valve and the plastic casing - it will stop the tabs from re-engaging while you do the other side. Be VERY careful as to not crack the tabs. And if it's cold (it was not here) warm the plastic tabs and valve holder first to make them pliable... Just a bit.

Car runs right and smooth. Smoother I dare say, which might have something to do with the original relief valve that gave no *relief*. After turning off the car before all this, I would get a HIGH fuel pressure (output) code - I think p0193 on start. When I would start the car after sitting sometimes the held pressure would be just around 70 at the rail. Pressures while running would fluctuate on the HIGH side of 55.3.

Now, with this "new" used valve, pressure drops to ZERO, or close, after turning off the car. Not sure what's going to happen at start after she sits a while. Maybe a long crank? Have came to that yet. smh. Tough times.

See "new" used valve with different last digits and letters. I'm grateful for it but it's still not the right thing. And I don't know, maybe I damaged the Oring on install again...? Can't see it. But I couldnt draw air back thru it once it was seated... What a thing!

Very very grateful that the pump can be removed and installed in 15min... If not for that I would be pulling my hair out.

The way I found it this AM.

Last 4 digits and 2 letter differ from the original. First string are exactly the same.


Old valve...#

 

That's similar to what I found, but 39psi is way below the normal running pressure. Needs to be nearer 70-80 psi.

I guess you could temporarily bypass it to see if the pressure drops immediately after you shut the pump off. Could you have a leak further downstream?

I had a look through the VDO website but couldn't find much:- just a complete unit for the 2009 XF.

Separately, somewhat OT, does the pump itself come apart - or is it one of these machine-pressed things that are designed to prevent intruders?

 

Hmm. I've heard/read that running pressure should be around 55.3 +/- a little up hills, take off - and that's what I'm seeing now. I jumped on the highway (after also changing the LH tie rod - the menace I bought the car from used to pull it around, non runner, by hooking the tie rod) today - she ran nice pressure pretty solidly at 55.3.

I didn't have a leak downstream before I started all this but it doesn't mean it's impossible. It been on my mind. Also, it's a pressure fitting with release tabs on the floor of the tank to send the fuel to the engine. Oring in the fitting, I thought possibly there as well. It's not holding pressure at all as soon as I turn the key off it quickly drops.

And yes, these pump assemblies come come apart into about 5-7 different peices... The little basket that holds the valve separates completely from the rest assembly. A few hose sections will. The top of the basket. When you have one in your hands, knowing how much they cost, it is a nerve wracking thing using tools to pry the bits and pieces apart...

I wanna post a link here and am very interested in what folks think about this "option"?
​​​​​
​​​​​​

 

For our 4.2L engines, the fuel pressure is supposed to be 55psi, but this is the pressure differential relative to the manifold pressure (there is a vacuum/pressure line from the manifold to the pressure sensor). When the throttle closes (low manifold pressure), the absolute pressure is lower than 55psi. For a supercharged car on boost (say, 12psi), the fuel pressure needs to deliver 67psi in absolute terms. When a car on boost suddenly sees the throttle close, that large difference in manifold pressure needs to be accompanied by the same drop in fuel pressure. I believe the pop valve does/helps dropping the pressure in that scenario. From prior posts, the pop valve differs between XK8s and XKRs, with XKRs having a higher pop pressure.

Best of luck, keep us posted.

 

Thanks Mertz... Really.

I think I know where I messed up. The top of the two oring seals. I don't think it's seated properly, my own error. The rings are an exact fit, I don't think any old ring will do. I am using the originals. Luckily I had two of the smaller lowers. Destroyed one. The top, I didn't handle it rightly. Not thinking, I placed it on the valve, lubbed it, and pushed into the housing. The lower one I placed in the housing and pushed the valve thru it. Stupid. Honestly, when I do some of this stuff I don't know what I was thinking (or not). I'll be going back in most likely on Saturday.

Started the car today, I built up pressure pretty quick, started up fine, but I know it's not right. Yup, be diving back in. Damn car, lol... Who's the boss!?!?!?

 

I want to thank y'all for all your help in this! Really!

I made the final "adjustments" almost two weeks ago and wanted to hold off before making any final pronouncements, lol. That always seems to get me - embarrassed, lol
So, things are good. All the problems after discovering the stuck pressure relief valve and trying to install the "new" one had to do with ME! My mistake was NOT setting both orings into the plastic relief valve housing before forcing the valve into its seat. To force it in evenly, I used (if I remember right) a 22mm socket that cleared the top barrel of the valve in the ID of the socket while the OD of the socket cleared the plastic frame of the valve holder. Tough to explain. I used a good smear of petroleum jelly to ensure there was no binding orings which will and DOES rip rings. This was dangerous as the rings are VERY specific and I was able to find neither THEM or the valve itself anywhere.

I wasn't able, but I hope someone somewhere finds that specific valve or a substitute valve with the proper specs. I looked and looked with no luck.

As it is now, running fuel pressure is just above or below the 55.3 mark, and when I turn off the car the pressure will drop to about 40-45. Key turn, with the 2 sec fuel pump bump BEFORE starting, to about 60psi, then on start, drops to about norm,,, 55psi +/-

Good stuff. I can't imagine having gone thru this with the normal procedure for removing the pump. I'm glad for my cut out in the back deck for pump access. Let see how long before Ill have to go digging around in there again, lol. OMG, my life.

Thanks again!