P1316 means the cylinder misfire is excessive and there is a risk of damage to the engine and catalytic converter, so Restricted Performance is imposed. Here's the published Jaguar definition from the DTC Summaries manual I attached to Post #9:



Resolving the cylinder 6 misfire will resolve the P1316.

Cheers,

Don

 

You can't check the fuel pressure without the engine running. When the key is turned to position 2 (II), what you refer to as "run," the primary pump primes the system with a short burst, then stops. When the key is turned to position 3 (III) or "start," the pump runs and continues to run after returning to position 2. You don't have to remove any coolant lines to get to the valve, just lift them up. Yea, it's a two-handed job. The only vacuum tube there is the breather, and it's easier to get to the valve when removed from the cam cover, but put it back in after connecting the fuel pressure gauge. If the injector harness is in the way, loosen the two nuts on the cam cover that hold the metal harness strip and it will move back out of the way. I would repair the frayed wires before doing anything else, if you haven't done so already.

 

Yea I didn’t want to risk bending the shader valve so I just took it all off for better clearance.

When the key was in position 2 it showed 19, when I let the car run for a second it went up to 21.
I will attempt again and let it run longer.

Also I have not been able to repair the wires yet as I’ve not had a day to myself. But oddly enough Cylinder 6 injector wiring is fine it’s mainly cylinder 2’s injector wiring that got the most affected.

 

Re ran the fuel pressure test and it came back at 40 PSI at idle and would rise when I gave it gas.
I also put a stethoscope to all the injectors and it does seem like injector 6 is a but more noisy or less noisy?? Hard to tell to be honest but it was for sure different than the others.

Here are the pins to the relays as someone mentioned earlier.




I’ve gone ahead and purchased 2 Delphi Fuel Pumps, 2 Delphi Fuel Strainers, and A-Premium Fuel Injectors. Should I purchase anything else that is needed or should be done?
Along with those purchases I bought the 2 CIRCLE GASKETS for the V8 top hat to the charge air coolers. I’m also looking for the 2 rubber hoses that go from the bypass valve to the charge air coolers but can’t seem to find them anywhere. Should I just DIY it at home n make some?
Il

EDIT: I’ve just cleared the codes and taken the supercharger belt off. I will update when I notice the check engine light pop up.

EDIT 2 : Check engine light and restricted performance came back not even an hour after clearing codes. But car ran great the whole day I changed fuel filter… weird.

 

98 XJR
I’m still trying to figure out how to put it in my signature

 

To edit your signature, click on your "name" in the upper right corner then scroll down to "Edit Signature."

Your fuel pressure looks good at 40 then going up with acceleration.

Do you know if the plates that hold the SC ducts between the outlet and intercoolers have been upgraded? I've attached the TSB with the part numbers.

That's all for today; football starts in 15 minutes.

 

The damage to relay on failing pump more important is on the inside power contact surfaces as this will burn / arc on pump starting to fail ) . Relay suggested to change on fuel pump motor replacement

Someone did recently indicated he was able to cut open relay and clean / sand

But agree 40 , PSI is good enough but 43 best at idle . there is a range the ECM ( injector pulse width ( time )) can compensate for

There is a short cut on pump change without removing tank , but may want to clean tank

 

I do plan on going through the backseat and cutting a hole through the top to access the fuel tank.
Is there anything more to it than just cutting a 6x6in hole to the right of the subwoofer?

 

Instead of cutting through the parcel shelf, you can cut a hole at the bottom area behind the rear seat and disconnect the fuel lines which will allow you to pull the tank back enough to get the fuel pumps out. You will need to remove the fuel filler neck from the car body as well. I've done this on five cars so far. Hole should be about 8 inches square starting above the body seem behind the rear seat. To reassemble the cutout, get some screw clips to secure it and cover with metal tape!
Also, cut shallow to in order to not damage the tank or lines behind the panel.

 

The relay internal contacts are the area of interest ( red circle ) , this is a generic pic and the actual X300 relays insides may be layed out internally different

The power contacts will be the only 2 as you move with your finger the 2 contacts together as they should be " relaxed " apart from each other and termed open and not closed ( together )

On fuel pump replacement observe the lines inside the tank as some of them have been reported come loose or off

There is an inside tank line diagram and those that have done it can attest to the diagram's accuracy

Hi Motorcarman and others , I have not done a pump replacement but a 1/4 inch by 6 foot siphon hose will drain most of tank and some tanks do have a siphon hose trap besides the upper no lead nozzle gate which has to be moved out of hay with inserted screwdriver , might as well change the main fuel fitter for good housekeeping

See page 60 of the Jaguar 801s doc coming , this doc covers your AJ16 engine but also includes the earlier inline 6 AJ6 and the V - 12

jagrepair.com/images/Training Guides/801S - 2000.pdf

 

I gave you Docs for earlier inline 6 X300 so will search for correct

For the 1998 you could have either the AJ26 or replaced improved ( steal sleeves ) AJ27

This brings about the difference in pin / wiring at the Mas Air Flow sensor connector that has tripped a few between the AJ26 and 27

There is an engine serial data plate location to identify engine model

 

Hmmm, I don't see a signature line in your post ...

So, the the rubber ducts from the SC to the intercoolers are "extremely old and torn," you have codes and fuel trims that point to an air leak, and the fuel pressure is within normal operating range. Am I missing something?

 

No that about sums it up
Although I don’t mind replacing these things as I probably should’ve done it when I undergone the rebuild.

The reason I didn’t replace the gaskets earlier was because when I had first put the engine back together when I rebuilt it, it ran perfectly.
(those gaskets are pricey too)

When it started to misfire and hesitate, I went around and sprayed easy start over every possible area that can pull air and nothing.
The only area I can think of pulling air is my Rear Main Seal. If that’s even possible.

 

Injectors and pumps came in today. Before I go ahead and start taking stuff apart, could anyone help me in figuring out where all the stuff outlined goes. Never touched the fuel tank so I don’t know what to expect .

The one I’m most confused about is the stuff in BLUE.



Do these pumps and injectors look correct for a 98 XJR?

 

The injectors for the supercharged may be different than the normally aspirated at least for the inline 6 noted in a TSB by color stripes on them

Might have to wait a week while your tank advice comes in or you can search in the box upper right corner

Might as well source for a new pump connector car side , it is a common type ordered through the local parts store

 

[QUOTE=Ant305;2894952]
Although I don’t mind replacing these things as I probably should’ve done it when I undergone the rebuild.

All of us DIY'ers have stories that fit that statement. I have a couple that come to mind over my morning coffee if you want to read them ...

The problem with the original design was they got sucked into the air stream. The updated clamp plates have grooves cut around the perimeter and the updated ducts have a rib that fits into the groove so they don't get sucked into the hole. With your ducts being old and tired, I suspect that the update has not been done. I checked the part numbers from the TSB and a lot of OEM suppliers list the A-bank plate, AJ86927, as discontinued, so if you do need to get the new plates, you're going to have to dig deeper than I did to find one. The other two are available; Harper Jaguar appears to have the best price at $71.24 for 86926 and $72.88 for 86928. Anyway, I would pull that stuff off as soon as possible to see what you're dealing with.

A lot of members on here have used the Delphi fuel pumps; I've stayed with the Densos so not much knowledge on the installation of those. The connectors are different, so they did send adapter wires, and my guess is that the pieces in the blue circle are to clamp those extended wires together. The pieces in the red box are the insulators to mount the pump in the bracket that holds it to the swirl pot. I have no idea what the stuff in the yellow circle is; wire? vacuum tubing? Before starting this project, search the threads for "Delphi Fuel Pumps" and "Fuel Tank." You'll get a good idea on what to do, especially on the tank. We all have our own techniques for that job. The one thing that's consistent with the tank is the size of the hole to get to the pumps. There's enough room to get a hand in there, but not much else.

Parker is correct that the XJR uses different injectors than the NA engines. You have the R injectors. If you want to verify, the XJR number is LCC1521AD and the NA number is AJ83967. You can see the difference in the pictures.

 

That’s great to hear, I need the XJR injectors and was hoping I didn’t need to return them.

If you can tell if these are the old or new please let me know.





Side Note: I took out the Fuel Pump 1 Relay and started the car, it ran but extremely bad. Is that normal or is this a good pointer that its Fuel Pump 2 that’s gone bad?

 

Can't tell if those are the revised clamp plates as the groove is under the rubber ducts. If the part of the plate that mates up to the duct is smooth, then they're the old ones. I do see oil on the top duct of the second picture, and the bottom one has an area on the left that looks like it isn't sealing too well with a lot of material missing.

Fuel pump 2 is a booster pump for the SC. I got a new laptop a couple of moths ago, so I "AI'd" (new term I just made up) it with a couple of questions. Here's the Q's and A's:

When does the second fuel pump activate on a 1998 Jaguar XJR?

On a 1998 Jaguar XJR (X308), the second fuel pump typically activates under the following conditions:

• High Demand / Heavy Acceleration: The secondary pump is primarily used to support high-load situations, such as heavy acceleration, where a single pump cannot maintain sufficient fuel flow and pressure for the supercharged engine.
• Engine Starting: Both pumps are often briefly activated by the Engine Control Module (ECM) when the ignition is first turned on to prime the system and ensure there is enough pressure for cranking.
• Redundancy (Failsafe): If the primary pump (controlled by fuse #7) fails, the car may still operate on the secondary pump (fuse #15), as it provides enough pressure to keep the engine running, though performance may be limited under high load.

Key Differences

• Primary Pump (Pump 1): Operates continuously while the engine is running and during starting. It is powered via fuse #7 in the trunk fuse box.
• Secondary Pump (Pump 2): Only activates when needed (typically above a specific RPM or throttle threshold) or during the initial start sequence. It is powered via fuse #15 in the trunk fuse box.

What RPM/throttle position activates the second fuel pump on a 1998 Jaguar XJR?

The second fuel pump on a 1998 Jaguar XJR activates at approximately 3000 RPM or under heavy engine load. The specific throttle position is not as commonly cited as the RPM threshold in technical discussions.

Activation Conditions

The Engine Control Module (ECM) manages the operation of both fuel pumps based on engine conditions:

• Engine Speed (RPM): The secondary pump is primarily triggered when the engine reaches around 3000 RPM to ensure adequate fuel supply for higher performance demands. Some owners experiencing issues have noted a flat spot in acceleration that clears after this threshold or if the secondary pump circuit is faulty, which corroborates this RPM figure.
• High Engine Load: Activation is also tied to engine load conditions, such as heavy acceleration, when the required fuel pressure (which can range from 45-65 psi when both are running) cannot be maintained by the primary pump alone.
• Initial Start-up: Both pumps operate for a brief period (around two seconds) when the ignition is initially switched on to prime the fuel system and build pressure before the engine is cranked.

The primary pump operates continuously whenever the engine is running, while the secondary pump is switched on and off as needed to meet fuel demands.

 

That last sentence above is interesting. The first time I had to replace the pumps, it was a slow process of pump 1 going out; hard starting and such to the point that it wouldn't start at all. According to AI, pump 2 should have turned on, but I had to have it towed home. Maybe I burned up #2 waiting for #1 to go out. The second time I replaced the pumps was preventative maintenance; they had been in there for eight years.

 

I wonder where AI found the 3,000 rpm specification? It is strongly implied that this information comes from forum posts rather than official Jaguar documentation.

I've just done a quick review of all the Jaguar AJ26 and AJ27 Engine Management Systems training manuals and Workshop Manuals in my library, and the only reference I could find to Fuel Pump 2 operation is on page 4-105 of publication T870A, Training Program - Jaguar Engine Management Systems and Advanced EMS Diagnostics - Book A. Here's all it says for the AJ27 engine (it is silent on the AJ26):




No further detail is given.

I did find that for the supercharged AJ16 6-cylinder engine, Fuel Pump 2 was energized when engine speed reached 4,000 rpm and de-engergized when it fell to 3,200 rpm.

If anyone knows of a more detailed explanation of AJ26/AJ27 S/C Fuel Pump 2 operation, I would be grateful if you could post it.

Cheers,

Don