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'99 XJR - Bad fuel pump work-around?

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Old 01-04-2010, 01:01 PM
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Default '99 XJR - Bad fuel pump work-around?

Hi - first post here.

My '99 XJR is dead in the water. Following info found in this forum, I chased down a fuel pump problem. Pump #1 shows an open circuit when its power lead is tested from the trunk fuse box.

So it is time to pull that pump out. Unfortunately, the car is stuck in an awkward place. I'd like to be able to move it a bit (without getting a tow truck involved!).

My question is this: if Pump #2 (the "high-speed" fuel pump) is good, could it be used to make a work-around for the failed pump?

That is, what if Pump #2 were patched in to Pump #1's circuit. Would that bring the car to life (so I could at least move it into the garage)?

Here is what I propose:

Circuit diagram (existing):
+12 => Relay 4 ====o Fuse #7 o========> to Pump #1
+12 => Relay 1 ====o Fuse #15 o========> to Pump #2


Proposed patch:
(A) Pull both fuses.
(B) Connect one end of jumper to left of Fuse #7 socket.
(C) Connect other end of jumper to right of Fuse #15 socket.

In theory, this should make Pump #2 fire up when the ECM tells Pump #1 to start.

What do you think -- asking for trouble, or a reasonable work-around?
 
  #2  
Old 01-04-2010, 01:27 PM
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What have you got to lose?

After you spend several hours pulling the tank you are going to replace both pumps anyway. Certainly sounds like it would turn on pump 2 and may well start the car.

Let us know.
 
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Old 01-04-2010, 03:01 PM
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You don't need to do any kind of wiring hack. The supercharged cars will automatically run pump #2 continuously if the relay for pump #1 is missing.

Just remove the relay for pump #1 and start. It may take a couple of cranks for the ecu to make the switch, but the car will run with only relay #2 inserted (assuming relay #2 and pump #2 operate correctly). You'll get the usual "performance restricted" message, but the car will be driveable.

The effect is intentionally creating an OBD error P1230 -- "Fuel pump relay malfuction: SC – When fault is detected, ECM – Operates fuel pump 2"

TTYL
David
 

Last edited by DavidB; 01-04-2010 at 03:16 PM.
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Old 01-04-2010, 03:57 PM
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Thanks for the suggestion, DavidB.

I tried pulling the relay for pump #1. Cranked but still no fire.

This did show "Restricted performance", and my OBD scanner reported a P1230.

But no go. So maybe both pumps are out. Though pump #2 shows about an ohm of coil resistance, so it seems like the wiring harness is intact. Hmmm.
 
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Old 01-05-2010, 01:06 PM
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Originally Posted by R as in Rocket View Post
Thanks for the suggestion, DavidB.

I tried pulling the relay for pump #1. Cranked but still no fire.

This did show "Restricted performance", and my OBD scanner reported a P1230.

But no go. So maybe both pumps are out. Though pump #2 shows about an ohm of coil resistance, so it seems like the wiring harness is intact. Hmmm.
Unfortunately, this did not work for mine either. I was stuck in my Daughter's Driveway... I figured my High Speed Pump had died long before the low speed did, and when the low speed went out, I was finished.

On the Up Side though. My car never had as much get up and go as it did after the two pump switch out. I figure it was always starving for fuel during pedal to the floor. Made a nice improvement on performance. (Not Mileage )

PS: Be sure to read the posts carefully to prevent damaging the outlet tubes on the bottom of the tank when removing it. I screwed up and pulled the tank while hoses were connected and pulled one of the metal tubes out. I was aware of this risk when I started, but I had help from my Hercules Son in Law and he pulled before I could say anything. Fortunately, after bending it back into place (A Major Pain in the Butt! No Room for Hands) I was able to plug it back in, and have never had a leak. I lucked out! I think I would do it again with Hoses connected, but I would be the one to pull next time. Removing hoses is almost impossible without dropping the Differential. You may have better luck with that.

Also, I used the Fuel Pumps from AutoZone. $99.00 ea and in stock. Major savings over Jaguar Parts. I think they are a match to some Ford Pumps is why. I just hope they last a decent amount of time. So far, so good. Edit: I had to trim the old Rubber Holders just a bit to get these to fit. Easy modification though with a pair of scissors.
 

Last edited by SuperSport; 01-05-2010 at 01:10 PM.
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Old 01-05-2010, 05:46 PM
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Sorry the workaround didn't work for you guys. I drove my car for an entire week on pump #2 because I wanted to wait until the weekend to tackle the fuel pump replacement job.

Maybe that feature didn't show up until model year 2000? It looks like both of you have 1999's?

TTYL
David
 
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Old 01-05-2010, 05:49 PM
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Originally Posted by DavidB View Post
Sorry the workaround didn't work for you guys. I drove my car for an entire week on pump #2 because I wanted to wait until the weekend to tackle the fuel pump replacement job.

Maybe that feature didn't show up until model year 2000? It looks like both of you have 1999's?

TTYL
David
Yes, '99, but I confirmed my 2nd Fuel Pump was dead, so the workaround might have worked if the pump was still good. Great Advice for those that still have 1 working pump as I was not aware of it till this forum.
 
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Old 01-05-2010, 10:01 PM
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Originally Posted by R as in Rocket View Post
Thanks for the suggestion, DavidB.

I tried pulling the relay for pump #1. Cranked but still no fire.

This did show "Restricted performance", and my OBD scanner reported a P1230.

But no go. So maybe both pumps are out. Though pump #2 shows about an ohm of coil resistance, so it seems like the wiring harness is intact. Hmmm.
I had the same problem,one pump had failed but because I hadn't push the car,I didn't notice the lack of preformance of running on one pump and there is NO codes because there is no sensor on the pumps to tell when they fail.But when that pump fails you are dead in the water..
 
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Old 01-08-2010, 09:01 PM
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Before diving in to the dis-assembly job, I did one last electrical test. Now it seems that pump #2 is also bad.

(Details: I dragged out a 15 volt/15 amp adjustable power supply, and plugged it into the relay socket pin that drives pump #2. Set the supply for zero volts, set the current limit to 10 amps, and slowly ramped up the voltage. Got a brief bobble around 4-5 volts, but when that cleared there was no more funny business. No noise from the pump and no current drawn even at a full 12 volts. So the pump is not responding at all.)

It smells to me like the wiring harness could be toast -- that might explain the funny resistance readings. I'll post an update after getting the tank apart.
 
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Old 01-09-2010, 02:13 AM
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There is a resistor in the wire harness, it goes bad. Also when I pulled mine the wiring itself had rotted. 180 bucks for the little 10 cent part with the resister slapped on it. P.O.S
 
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  #11  
Old 01-09-2010, 09:21 PM
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Originally Posted by R as in Rocket View Post
Before diving in to the dis-assembly job, I did one last electrical test. Now it seems that pump #2 is also bad.

(Details: I dragged out a 15 volt/15 amp adjustable power supply, and plugged it into the relay socket pin that drives pump #2. Set the supply for zero volts, set the current limit to 10 amps, and slowly ramped up the voltage. Got a brief bobble around 4-5 volts, but when that cleared there was no more funny business. No noise from the pump and no current drawn even at a full 12 volts. So the pump is not responding at all.)

It smells to me like the wiring harness could be toast -- that might explain the funny resistance readings. I'll post an update after getting the tank apart.
That failure is common on both xkr and xjr cars.When I replaced my pumps the car had less then 40k Miles,other on the forum have had the same problem.It surprised me when I looked at the harness,the small gauge wires and small connectors that have to carry the current of the pumps.

The other thing that some of us had in common is that we store our cars for 4 to 6 month over the winter.

The job is not diifficult,it just take time and patience,the dealer wanted$1300, to do the job.The parts cost me about $350.
 
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Old 01-09-2010, 09:55 PM
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Eagle, do you put StaBil ( http://www.goldeagle.com/brands/stabil/default.aspx) or some such in the tank before storing the car? I wonder if gummed up fuel might be the culprit in these pump failures?
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Last edited by Markus; 05-14-2011 at 08:55 AM.
  #13  
Old 01-10-2010, 09:34 PM
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Originally Posted by Markus View Post
Eagle, do you put StaBil ( http://www.goldeagle.com/brands/stabil/default.aspx) or some such in the tank before storing the car? I wonder if gummed up fuel might be the culprit in these pump failures?
I use both Stabil and Seafoam in the tank before I pump them into storage.I looked at the stainers and took apart the bad pumps and no sign of gum.I also use a top tier gas and according to their spec the gas should be able to last in a full tank for 6 months without major back down.
 
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Old 01-11-2010, 09:42 PM
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I got the tank out today.

All the wiring is fine.

Both pumps are dead. Maybe I'll do a post mortem if I can get them apart.

A couple of points for the next person who tackles this:

1. Autozone has a cheap set of line disconnection tools. Part #25052; $8.39. These seem to be the same as pictured in the writeup at http://skjagtech.co.uk/support-pages...placement.html

2. With the car on jack stands, the best position for me to tackle line disconnection was as follows: I inched the creeper forward from the rear of the car until my nose was just about even with the rear of the prop shaft (feet to the rear), arms reaching around the outside of the parking brake cable, then reaching in and upward until my elbow was just past the edge of the muffler. As others have said, it helps to have long, skinny arms.
 
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Old 01-11-2010, 10:08 PM
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There seems to be a high incidence of both pumps failing at the same time. That seems strange to me, since they get very different amounts of run time. Maybe they fail with age as often as with usage?

I'm glad you found your issue, I know the fuel pump replacement is no fun in these cars!

TTYL
David
 
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Old 01-14-2010, 09:12 PM
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Default Fuel pump autopsy

I was curious about why the fuel pump(s) died, so I decided to take one apart.

First, I pried off the bottom (the inlet side of the pump). This revealed a small plastic turbine that spun spun freely. No hint of gumminess or binding. So the bearings were not at fault...

Next, I attacked the top. By peeling back strips of the outer metal surround, it was possible to remove the white plastic assembly that holds the output port and electrical socket.

That revealed the armature in the body of the pump, with its copper commutator looking in fine shape. All windings showed good continuity, so the armature was not at fault, either...
http://i823.photobucket.com/albums/z...commutator.jpg
Name:  Good_commutator_1.jpg
Views: 704
Size:  3.1 KB

But examination of the top assembly revealed the problem: One of the brushes was stuck or worn completely flush with the housing, and thus no longer able to make contact with the commutator! It is the top brush in this photo.
http://i823.photobucket.com/albums/z...ad_brushes.jpg
Name:  Bad_brushes_1.jpg
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At this point, I don't have a good explanation as to what would cause rapid wear on only one brush.

One possibility is that the plastic holder deformed under heat at some point, and froze the brush in place. That might have happened during a brief electrical overload -- perhaps some small contaminants in the fuel caused the pump to bind slightly, so it drew higher than normal current until the matter was flushed through the pump. Still, it's hard to see why only one of the two brushes would have been affected, since they pass equal current.

Anyone able to read these tea leaves?
 
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Old 01-14-2010, 09:46 PM
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Thanks for the pictures and the writeup on the pumps.Nice Job.
 
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Old 09-08-2010, 03:03 PM
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Trying to determine which relay is pump 2's relay none of them are marked and I cannot get the info from the jaguar web site because its unavailable??? Can someone anyone help!!!
 
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Old 09-08-2010, 03:10 PM
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Originally Posted by Dmello1 View Post
Trying to determine which relay is pump 2's relay none of them are marked and I cannot get the info from the jaguar web site because its unavailable??? Can someone anyone help!!!
Hopefully, this will help.
 
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Old 09-08-2010, 04:10 PM
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Thankful for the response but it says I don't have permission to access the page what do I do now???
 

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