Having seen the woes of replacing a dead fuel pump I'm wondering if there isn't a better solution for later non return flow models.
This
SHOP4RACE. Bosch. BOSCH 044 fuel pump
(for example) delivers enough pressure and could be mounted externally, leaving the old pump module in place and installing a new pickup into the top of the tank with it in-situ.
Maybe this is a stupid idea with some major pitfalls, I don't know.
I understand that the PCM switches the pump on and off as required but I can't find any details in JTIS of how it really works.
I don't imagine it would know what sort of pump it's operating.
Can anyone point me at more detailed information ?

 

Replacing the pump really isn't that hard. I thought it was going to be, but once I actually did it wasn't as bad as I had imagined it to be. The PVC tool that Avos invented makes all of the difference. I can't imagine doing it without the piece of PVC. There's obviously a learning curve, but the last time I did it it took me less than an hour to drive the car onto the ramps, disconnect the fuel line, pull the tank, pull the pump, reinstall the pump, reinstall the tank, reconnect the fuel line, and drive it off the ramps.

If you'll pay for my ticket to France I'll do yours for you for free. I don't mind flying coach.

 

I just thought of something. I still have my PVC tool, which I'll probably never use again. I don't know how much it would cost to ship it to France, but if you'll pay for shipping I'll send it to you. It makes the job about 90% easier.

 

That actually may be cheaper than paying a dealer to do the job.

 

That's very kind. You'd be most welcome here - free B+B and all the wine you can drink -and no need to fix the pump!
It isn't that expensive to fly AA to Paris and THEN you get to take the TGV (200 mph) here.
Many of us owe our Jag ownership to your de-mystifying of so much of the arcane arts.
Thanks for the offer of the Avos Device - if I did opt for the original pump replacement I'd take the Gordian Knot approach and cut the tube. A stainless 10 mm push in fitting costs a few $$ and removes (as you say) 90% of the PIA.

 

Steve I wouldn't cut your tube, Rev. Sam's right it's not that hard of a job. I just did it a couple of months ago. I replaced both pumps with Boschs. with a total cost of $180.00 for both it took about 10 minutes to fab a tool out of electrical conduit. My biggest problem was I couldn't get all of the gas out of the tank. I could not get pass the neck for some reason. so when I took the pipe off it was running out. I took a 10mm allen screw and put a couple of O-rings on it and was able to plug it. then it stopped leaking. When I was able to pull the tank back far enough to open it up I then was able to pump it out. took 3 or four hours and that wasn't constantly working on it, I took a few breaks in between.

 

Thanks Doug,
Mine has the $900 pump and I seriously baulk at paying that.
The advantages of an external pump are obvious.
If it turned out to be a simple alternative I'd work out the kit needed to do it.
The pump's fine at the moment but 80K miles is coming up and I've seen a lot of folk having problems at that sort of mileage.
It looks from other posts that the pump is petrol cooled. If you keep the tank full they last forever. Great design!

 

The older Jaguars used to circulate fuel at full pressure all the time. What was required was used and the remainder returned to the tank. The main problem with this circulatory design is the fuel temperature rises and fuel vapourises. This gives the characteristic 'whoosh' when the fuel cap is released on the early XJ's.

The XK8 delivers only the correct volume of fuel under all demand conditions at a constant pressure differential with respect to manifold absolute pressure.

There's two sensors in the fuel rail - a Fuel Temperature Sensor and a Fuel Pressure Sensor. The ECM/FPM uses these inputs to adjust delivery pressure from the pumps. To give this metered delivery, the pumps can't just simply be ON or OFF but must also be speed controlled?

Graham

 

Graham,
I'm guessing here but from what you say the pump driver module probably uses PWM to control the DC pump motor in which case it should control any DC motor.
Rather than just a 'bang bang' pressure switch it must apply proper feed back so shouldn't care about the motor provided it can put out enough amps to drive it.
Looking at 2004 XK8 XKR electrical the fuel pump is driven directly from the REM by two wires, there are no sensors in the tank module.
As you say the ECM has a bus going to the REM which controls the pump drive.
I'll bet €150 for a Bosch pump that it will work.

 

Steve,

As the pumps contribute nothing to the control mechanism, you should be able to use alternatives. The only risk appears to be throttle body calibration which is manufacturer set (?) and not even adjustable with the WDS.

If you're using the 10% ethanol that passes for Euro SP95 in France, you could be into pump replacement faster than you'd like.

Graham

 

Isn't 'Green' fuel glum. We've had to spend €1500 on an approved tank for our tractor 'New Wave' biodiesel. 10 % bioethanol. Result 10% reduction in output power so we use 10% more fuel.
I'm (again ignorantly) assuming that the injector cycle expects fuel at pressure P and temperature T and opens the injectors long enough to squirt just the right amount of motion lotion into the pot.
I suspect the pump driver isn't concerned with fuel T° - that seems more important to calculate density and injector flow rate to get the 'squirt time' right so the ECM is ONLY driving the REM to drive the pump to keep the desired pressure at what it should be.
So the throttle body vane waggler shouldn't care about what the pump is up to as long as it's delivering enough pressure at the flow needed.
Sorry that's a bit of a convoluted statement.

 

I would NOT recommend cutting the fuel line. The fuel line connects to the tank at the bottom of the tank. When you pull the tank out the little stub of fuel line is going to get bent, or it will bend the tank. I don't even know if it would be possible to pull out the tank with a stub of fuel line sticking out because the top of the tank is very close to the upper part of that little cove which the tank sits in. Then, putting the tank back in would be even harder.

Honestly, remove the fuel line is a piece of cake. If you use Avos' PVC tool it's not as difficult as every has made it out to be. I completely understand why people complained about the difficulty using the short little tool you get at the auto parts store. There's just no room to get your hand up in there to use the tool. But with the long tool it just takes a matter of seconds.

 

The plastic tube is not hard to make, and makes the job to remove the lines really easy.

But be carefull when choosing another pump for the 4.2 cars returnless system, the ECU also has some rationality checks, so if the pump would flow more then the stock one, you could go into limp mode.

 

Avos, I really don't wont to go into limp mode......
I remember the contraceptive pill that was hard and the man put it into his shoe to make him limp.

 

I'm sure I've read the flow rates for the XK8 and XKR pumps are different but can't find the reference again. The part numbers for them are different.

Graham

 

You must hold the land speed record for the job.

The shop I was forced to use due to being stranded took over a month *and* charged nine hours.

 

My mechanic put my car up on a lift, and a screw jack under the differential. He dropped the differential 2" so he could easily get to the quick attach fittings.

2.7 hours book value job @ $50 per hour plus a $50 fee for the tow (rollback), and I was up and running for about $200 including sales tax.

RockAuto.com is getting $71.79 for the popular Airtex E2471 pump (that fits a Taurus), and you also need to buy a strainer filter. You can usually find internet coupon discounts of 5% for RockAuto.

 

Thanks all. Point taken about not cutting the pipe.
If it ever stops raining I'll put a storage scope on the pump drive lines and see what the REM is sending.
I'm a bit worried re Avos' suggestion of a reality check but I can't believe there'd be a complete matrix of flow rate vs pump drive in the ECM. There can't even be an 'I'm flogging a dead horse' setting since (I beleive)no-one reports an error code when the pump dies.
I'll report back when the Sun shines.

 

From the 2003 training guide:

Available here, interesting read.
http://matt.zenfolio.com/2003-xk-ser...ning-guide.pdf

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.

So any alternative pump would need to be happy working under these conditions.

 

Interesting stuff. The R pump is a gear pump so there should be a good relationship between rpm and output but I can't believe it works on dead reckoning by just telling the pump to turn at X rpm. There must be feedback (I hope or this idea is a non-starter).
Edit
The plot thickens
https://www.carpartsdiscount.com/aut...tml?3593=52742
these guys claim the in-tank pump is a Bosch 044 and an external 044 can also be used.
I've emailed them for more info.