My 2004 Vanden Plas quit on the freeway while driving 70 mph and would not restart. Got a p1338 code with generic scanner. Seems that the fuel pump is bad. I get mixed opinions on whether this normally aspirated 4.2 XJ8 has a fuel pump driver module or not. I know the XJR's have them, but I'm not clear if mine does. Does anyone out there know? Any help would be greatly appreciated.
Also, is the pump driven by 12 volts or a reduced voltage by the module, if it has one? I was going to apply 12v to the disconnected pump to see if it runs, after I figure out how to access it.
Thanks in advance for your help

 

I can't help re the electronics but I suggest you measure fuel pump pressure

it should be about 55 psi.

Fuel pumps can fail "just like that".

 

You code translates to "Fuel pump feedback control inhibited"

In other words the REM (rear electronic module) can not tell how fast the pump is pumping

In both the NA and SC versions fuel pump 1 is controlled by the REM directly but uses signals from the ECU
The REM regulates the fuel pressure by regulating the speed of the pump.
The code you have is the REM can tell how fast it is pumping and therefore cant regulate the fuel pressure

This may be caused by a dud pump or an issue with the REM

I would first check your battery voltage as the REM can get corrupted with low volts
Make sure the volts remain above 12.2 and test this while cranking the engine

The next thing to do is test the wire are not broken and clean the contacts at the pump and REM

Finally get the codes read with SDD

You can access the pump under the rear seat. You will find 2 access holes.
One will be the fuel pump and the other the transfer pump. The Transfer pump is just for leveling the 2 tank halves only one supplies fuel to the engine

AS for the SC versions (XJR/Super V8) they have a second pump (fuel pump 2). This is driven by an extra module (FP2M) that is controlled by the ECU

In other words you only have one pump so it must be pumping or you would have no fuel
The issue is the REM does not know how fast it is pumping and is unable to regulate the pressure
It may be a fault at the pump but the most likely causes are a corrupt REM due to lack of volts at some point or a broken/poor contact on the feedback wire

Cheers
34by151

 

The pump is not running at all. no fuel pressure. After disassembling the removed pump assembly, I put 12 volts to the pump and it would not run until I smacked it on my bench, and then it ran for a few seconds. I believe the pump is bad. I ordered an after market pump assembly, but I was wondering if anyone knows if a regular "in tank" pump of the same dimensions would work. I have a new one from about a 90's Mitsubishi, that looks identical, except for the plug receptacle. Would there be a risk of ruining the REM if it (Mitsubishi pump) were installed?

 

You could try it but I'd recommend getting a pump that is made to fit the car be it oem or aftermarket

Cheers
34by151

 

+1 on that

You may find this useful.

https://www.jaguarforums.com/forum/x...50-xj8-105816/

 

Installed the after market fuel pump, all is good, check engine light went off without a reset, road test went well. Only problem is, the fuel gauge does not read the same as I remember it at the time the fuel pump quit, but that was a week ago, and I'm old.

 

Good to know that an after market fuel pump will fit and work.

If you have a problem with the fuel gauge in future it is usually corrosion on

the contacts which in theory can be solved by cleaning or replacing.

It may also sort itself out like mine did.

 

I don't want to mislead anyone. The pump I installed was an after market pump assembly, specified for Jaguar. My concern with the fuel gauge is that it is new, came with the new pump. The (Mitsubishi) pump I had on the shelf looked the same, but had subtle differences that would not allow it to fit the housing and be reliable.