Okay.
After 2 days of a weird whining noise from the back end I finnaly discovered what the issue was.....
Not the oil flow in the shocks... sadly.. thats still an ongoing issue...
No, its the fuel pump.

Diagnostic process:
Engine wont get going. Has spark, no airproblems, no errors.
Whining noise isnt present....
When the whining noise returns, the motor picks up and no problems.
When the noise goes away, the low RPM returns and of late its had sputtering issues....
So....
Fuel Pump is dieing....

Whats the process for replacement?.
In my old Volvo there was a handy hatch / pannel in the trunk over the tank where you could (with some difficulty) remove the entire pump.
Im guessing the XJ6 isnt as helpful and I have to drop the tank??

Any advice?

 

Hell yea!! The fuel tank is in the back!.
:-)

So I dont have to drop 15Gallons of fuel on my head like I did with the Volvo!? YeeeHar!!.
This will be easy!.

Now, I just wish the pump wasnt $90 lol.

 

Adrian,

Your '88 XJ6 is known in the Jag world as an XJ40 Model. Dont panic, this confusion is "normal" for most owners due to badging, life goes on.

One of the "friendly" mods may relocate this to the XJ40 area.

That $$ for the pump is pretty reasonable, considering some I have needed to replace over 40+ years. Like $650+ for the BMW 740, scrapped the car, easier.

Dont forget to renew the fuel filter whilst under the car.

Just take care with fuel spillage that will occur, I dont believe the system will actually "syphon" like the XJ-S does, but be prepared.

 

See, this thing is listed as an XJ6.
And the VIN returns an 87 model

Anyway.
Pump replaced.
I found it slung under the car. :-)
Soooo glad its not an intank job!

Tools used:
Screwdriver, 8mm, 9mm, 18mm, 19mm wrench and a 3/8 socket extention (used to jam in the fuel line to prevent gas going everywhere).

I inspected the old pump and found some alarming rust deposits in it.
I think I need to take the time later to flush the gastank...?
Ill probably back wash it, clean it, test it and keep it for backup.

But the filter and pump took a little under an hour to do once the car was on the ramps. :-)

 

Sweet outcome.

The '87 is a "grey area" as you have found, but the fact your pump is under the car, and you have 1 fuel tank in the boot (trunk), does in fact confirm it is the XJ40 version of the XJ6. The S3 predecessor has 2 fuel tanks, one each side, and the pump, or in some cases there are 2 pumps, in the boot (trunk), as is the fuel filter.

Rust is probably from fuel over the years, and maybe Ethanol fuel has been used, and that does have a history of rusting steel tanks over time, at least down here.

 

Ah cool. Thanks for the tip.
XJ40. Ill have to record that somewhere and change forums.. lol.

Yea, that was something that came up on the search at the parts store.
But only the one pump was listed in the parts list.

The rust problem... yes indeed.
They have been using ethanol here for about 7 or 8 years now. "No more than 10% per volume". So some of the older cars that have steel gaskets are having issues. When I replaced the fuel pump on my old volvo ('79 262c), I had to drop the tank and took the time to clean it out. The amount of rust and crap was amazing!. Now after seeing the rust from the old fuel pump filter Im tempted to set aside a day shortly and totaly remove the tank from the Jag and do the same. Though I was told that just flushing the tank with the fuel line unhooked would be just as easy.

 

AH, it is clearer by teh day.

The tank really should come out and be flushed, as you did with the Volvo. The fuel line type of flush will NOT get the larger pieces of crud out, and they could be blocking the outlet fitting so as to starve the pump for supply fuel. This blockage will lead to another pump failure, and a noisey pump, and worst of all, quite poor performane from the engine.

There is possible a sock type of arrangement covering the outlet hole inside the tank, and that would be quite badly clogged in my opinion.

 

I'll consider my wrists well and truly smacked Grant, how could I have not spotted a required thread move LOL

Best of luck with getting the tank out, I didn't enjoy removing mine (stuck fuel lines under car, with internal FP)

When you put it all back, pay attention to the filler neck drain, if it is not seated correctly your trunk fills with water. How do I know this you may ask. Doh

 

Yea. After a quick drain and flush...
My conclutions are:

A: The whole tank needs to come out and get flushed.

B: I need to get a new gas cap. The crack is not letting pressure build up.

C: A new filter might be a good idea. But back washing the existing one might be a quick fix in the mean time.

D: The whole tank needs to come out and get flushed.

 

If and when you take your tank out,and after you have cleaned the crap out of it ,I would suggest coating the inside of the tank.The absolute best coating is available from caswell plating,leaves a smooth uniform thickness and you can use any type of fuel in it (gas,alcohl,or nitro)the stuff is amazing,also works with fiberglass tanks for motorcycles.