As many of you know the early (4.0 litre) XKR has dual fuel pump design. There are two identical pumps in the fuel tank, connected in parallel (not series as has been erroneously posted). The primary pump runs constantly and the secondary pump kicks in under boost for added fuel volume.

After discovering that I was running on just my primary fuel pump for months, if not years, on my 2001 XKR, I did some browsing through various threads on fuel pump failures. It seems as if many reported failures involved both pumps.

I am convinced there are a lot of us driving on one pump. When the secondary pump fails there is some loss of power, but it is not 'in your face' dramatic and there is not a fault indication. When the primary pump fails the ECM is programmed to utilize the secondary pump as a backup. So in either case one pump will run the car.

Since fuel pump failure is not particularly rare, every XKR owner should check periodically, perhaps at each oil change interval, that both his or her pumps are functioning. This will assure you have maximum power (ie; fun!) and also that you have a backup should one pump fail.

In order to test the secondary fuel pump pull the primary fuel pump relay. Then try to start the car. The car will start and stall about half a dozen times, but eventually the secondary fuel pump will be switched to the backup role and then run the car normally from that point on. If this does not happen it is time to check the secondary fuel pump circuit (fuse, relay) and if they are OK, the secondary fuel pump and/or Link lead inside the tank has probably failed. (Of course, reinstall the primary pump relay when you are done).

In order to test the primary fuel pump, simply pull the secondary fuel pump relay. If the car does not start you are already running on the secondary pump in backup mode, and the primary fuse, relay, pump or link lead has failed.

I think it will be very informative to do a poll as people try these two tests to see how many more of us are running on just one pump.

 

some additions ...

There are two small telltales for a failed pump. Detonation will be encountered on heavy throttle climbing hills. Or, prolonged cranking.

The reason for this is that the ECM is only able to post a fault for a failed fuel pump primary coil and not the actual pump or the power circuit. The other possibility is inadequate pressure.

The normal operating roles of the two pumps as documented by Avos are as follows:

initial fuel rail priming - secondary pump
running - primary pump
heavy demand - primary pump + secondary pump

Another way to test is to use make a jumper lead consisting of a male spade connector, a foot of 14 or 16 gauge wire and an alligator clip. Connect the alligator clip to the battery power stud in the fuse box and insert the spade into the relay connection leading to each of the fuel pumps in turn. The pump should be heard spinning. The jumper lead can then be stored in the trunk in the event that it is needed in an emergency to jumper the circuit. Testing this way avoids having "restricted performance" lights due to the ECM detecting a missing relay as a bad relay.

If a car is usually not in high demand mode, the secondary pump can suffer from lack of use as it only comes on long enough to prime the fuel rail. If the fuel system is in good shape, the pump will get very little exercise. Given the effects of ethanol, this is something to be avoided. If a secondary pump has been pickling for some time, it can fail within a few miles of being pressed into service after the primary has failed.

On my own car, I added a small control box a few weeks ago to be able to balance the fuel pump usage. This was posted in the X308 section at the time. It is two SPDT toggle switches potted with epoxy in a used tic-tac box attached to the fusebox with double sided tape. The taps were made in the trunk harness close to the entry to the fusebox.

The switches control the primary circuits on the two fuel pump relays and allow selection of the fuel pump to be controlled by each relay. This way, the roles of the pumps can be reversed to even out usage patterns, or both pumps can be forced to either relay. This modification has to be top quality because if it is not reliable, a failure can strand the car just as easily as failed pumps.

Once the system is in place, it is probably sufficient to do a role reversal at perhaps each change in the four seasons. Make the change with the ignition off so that the ECM does not see a "missing" relay during the change. If the jumper cable described above is also in the trunk, it would only take a couple of more minutes to verify that both pumps are still spinning.

 

Thanks for the added info plums.

On my particular car, I never saw detonation or particularly long crank times even though my secondary pump was dead and the link lead filter circuit was fried.

Your pump toggle assembly is cool idea.

 

All very good and relevant information.

Similar to WhiteXKR, My car seemed to act normally before winter storage. In the spring, both Pumps inoperative and were open circuit.

Had an independent garage replace both pumps and harnesses.

Cut one pump apart and the brushes looked perfect. Wiggled them and continuity re-established. But since pump was cut apart, couldn't operate it.

Banged other pump against workbench and continuity re-established. However, it still would not run, just draw current.

Prior to failure, I had always managed to use non-ethanol fuel, no pump failures. After ethanol-only fuel was available, first winter storage produced 2 bad pumps.

Now, I make sure to "Exercise" the Pumps during Winter Storage by jumpering 12v to them every several weeks.

To properly balance the Pump usage, Jaguar SHOULD HAVE alternated the Primary/Secondary usage with each engine run sequence - would have been easy to do.

 

Ok, out of curiosity I went and did this fuel pump test. I removed the first relay "fuel pump #1 relay" and nothing, the engine turned over and sounded just like it normally does, but did not start just turned over and over.

I replaced the #1 relay and pulled Fuel pump #2 relay started right up.

The relay #1 was black and the relay #2 was brown.

I put everything back together and the Jag started right up with a check engine light and the car in restricted performance mode.
I drove the car 4 or 5 miles and still the lights were on. I read the codes, there were 5 codes P1230,P1642 and P1672 one was duplicate and the other P1000. I erased codes and the engine light turned off but the restricted mode stayed on, I drove another 5 miles, stopped and started the Jag's ignition again and finally the restricted mode moved on. Turned off!

So I am guessing I do not have a secondary fuel pump, since the car turned over but did not start with #1 relay removed.

Are we sure I have 2 fuel pumps? 2001 XKR.

The car runs just like it always has. Is it worth taking in and having the second pump replaced?
Thanks for the heads up.

Happy Holidays and
Happy Motoring...

 

Since the #2 Pump did not come on and replace the #1 Pump, your #2 Pump is probably Inoperative.

You should try jumpering 12v directly to #2 and listen for Pump 2 running (with Engine Off, in a Quiet area).

You can remove the Pump #2 Relay and, using a short jumper wire, connect the 2 Socket Contacts that are Opposite each other and also Perpendicular to each other ( | ▬ ) to activate the Pump.

 

More than likely Pauls right I replaced both of my pumps last year. The main pump went out. The secondary was OK. I replaced both, no use doing only one. I replaced them with Bosch pumps, a lot cheaper than Jaguars prices.

 

Are you sure you identified the correct relays?

The relays are square cubes, not the rectangular ones. Always brown unless they are non-jaguar. The rectangular ones are the "mini-relays" and black.

 

On mine, the first pump failed on the way home from the grocery store. Left a bag there and had to go back 20 miles. (specialty grocery store). On the drive out with the yellow light lit, I'm thinking "how bad could it be ... the non SC cars only have one pump to begin with."

Nope, made the drive, parked properly instead of double parking, got the bag ... umm, no start. Cost a midnight tow + 10 labor hours + 4 weeks of excuses because of bad shop selection. The shop was a poor third choice behind having it at home with the wrenches out.

That's why people asking about limping it for a few weeks get the advice to not risk it.

It's also the reason for the two switches and tic-tac box.

A Mk III Supra Turbo has one Denso pump and people run them for 25 years without failure. It certainly isn't a big topic for owners. So maybe all this complexity is not really a good thing. With one pump, it gets run all the time.

Come to think of it ... is it mostly SC owners who have pump trouble? If so, then it has to be that system of mostly using one pump over the other.

 

As Shown:

 

I would imagine the failure of the primary pumps is equivalent in both XK8s and XKRs. It is the secondary pump failure that is somewhat insidious.

As plums said, it sits the 'pickling' in fuel most of the time, and even though it gets a little use at startup and heavy throttle, I think the lack of use takes a toll on its life. The in-tank filter on my secondary pump was dark with fuel deposits, while the primary was clean. I think that there is a clue there.

It is really a shame that the car does not monitor this pump. It is a similar situation with the intercooler coolant pump. Both of these pumps can go out and reduce the performance of the supercharger system, yet it is easy to be oblivious to either problem.

 

Ok here's an idea for RealGauge V 2.0 then. The coolant temperature sensor is relatively cheap, an additional sensor could be added to the SC coolant system. Add a DPDT switch or cabin controlled micro relay under the hood and you switch between reading the engine or SC coolant. If you really want to get fancy, have the stalk control the sensor selection.

For the fuel pumps, a push on/push off switch could be mounted such that it is actuated by opening and closing the trunk lid. Each time the trunk is opened the fuel pump mode is changed. That way the pumps are alternated as often as the trunk is used. Most people use the trunk more than twice a year

 

Yes, I have identified the relays based upon the pictures.
I have not changed any relays in the trunk fuse box square or rectangular and as you can see in picture, I have both brown and black relays. both colors have the Jaguar leaper and the name imprinted on them, so they must be factory OEM relays!

 

Hi there - I'm chasing a fuel pump issue on my 2005 XKR - it doesn't have the two fuel pump relays as shown in this diagram... Looked on jagbits.com and it seems that the 03.5 to 06 just has one $900 fuel pump. Has anyone had to replace the singular fuel pump in an 05 XKR? If so, did you find a more economical pump than the OEM one? Or anyone offering core exchange... a fuel pump for the cost of a quaife LSD, too funny,

 

Correct the 4.2L has a totally different pump design.

Here is a slightly better price: 2005 Jaguar XKR Parts - Direct JPLV Porsche Parts.com

but...

Are you sure it is the fuel pump? What are your symptoms? Do you have any OBDII codes? Can you read the pressure over OBDII? This system is electronically regulated, so many faults can be diagnosed with an OBDII scanner.

If the car is derivable, PM me if you want to stop by (I am in Arlington) and I can read your codes with an AutoEnginuity scanner.

 

OK, just saw your other post. Please do not multi-post.

Since you are new here you may have to email me.

You can reach me at "whitexkr 'at' comcast.net" or through my website below. If you are not parked too far away I may be able to come out with the code reader.

 

Pah. Just replied in the other (another) thread of same issue.

 

I tried this and my pumps were working and I got no engine codes from pulling the relays one at a time.

 

I didn't see another thread, at least on page 1 at this time. But my secondary is out. I had no idea about the pumps setup until taking my XKR to motorcarman earlier this year. He told me my secondary was out but I probably wouldn't notice it, nor was it critical. Regardless, something is broken and I must fix it now! It's on my list to have him do on the next trip there. It'll be interesting to see afterwards if it performs any better, though its job of priming the fuel rail when it's not really there at the moment concerns me. Haven't had any issues though.

 

Howdy folks:
I just did the jumper test and fuel pump relay #1 activated a pump while fuel pump relay #2 would not activate a pump. (fuse #7 tested good)
I had just assumed that fuel pump relay #1 activated the primary fuel pump and fuel pump relay #2 activated the secondary fuel pump but that was before I checked my PDF file 2002 XK8 Range Electrical Guide.(AJ27 SC Engine Management Part 2 fig.04.4)
Fuel pump 2 relay pin 5 OY lead runs to fuel pump 1 and fuel pump 1 relay (#4) pin 5 NW lead runs to fuel pump 2. (just the opposite of what I would have assumed)
My question is which relay and pump numbers correspond to primary and secondary and is there a misprint on my copy?
I am just confused and curious, but at any rate, I feel confident that I can make the repair.
Thanks all.