Finally got the plates for my 1986 XJS V12 yesterday. Engine rebuilt, runs beautifully at tick-over.
New petrol pump (Bosch), from D. Manners, installed after changing fuel filters, cleaning the tank etc. Makes a rather loud noise even from startup, plus that a good, hard acceleration is impossible; the engine either gets too much petrol or to little (I think), engine almost chokes under acceleration. Had to be really gentle on the pedal to even get it to 70 mph on the way home.
Has anyone experienced this before, and found the solution?

Cheers

Ronnie, Moss, Norway

 

Hi mrbungle

Stating the bleedin obvious but have you put the Fuel Filter in the right way round?



Making sure the Fuel Filter is the Right way round.

 

Thanks for your reply. And even though I am sure it was put in the right way (by a mechanic, not me), I will nevertheless check it come Saturday. Sometimes even a trained mechanic can make mistakes

Cheers

//Ronnie

 

Hi mrbungle

I wouldn't know (Lol)

I'd let a Mechanic loose on my Car only when Hell Freezes over.

 

Hi Orangeblossem wondering when you are going to get your Mechanic?

Hell, California, U.S
Hell, Michigan, U.S.
Hell, Grand Cayman, the Cayman Islands
Hell, Norway, a village in Stjørdal
Hell Station, a railway station at Hell, Norway
Hell Creek, a place in Montana notable for Cretaceous dinosaur fossils

Most of these towns freeze in the winter!

 

Hi Afterburner

When Hell Freezes Over of course.(Lol)

 

Oops

 

Again. Apologies.

Mods can delete these. Apparently posting anywhere posts here for me.

 

Normally the fuel pump making a noise is caused by a blocked sump tank filter or rubbish in the sump tank. It almost certainly needs cleaning out and a new filter (18 below). You have fuel starvation probably. Once that is done, post again, as if the car needs catch-up maintenance, ther will be other things to do before it runs properly (eg distributor work, plugs, HT leads, throttle sensor). But the sump tank is the place to start.

 

Hi mrbungle

If you have to drain the Sump Tank, this is where you do it.

Under the Car on the Same side as the Sump Tank (Drivers Side on a UK Car) almost in a straight line across the Car from the Back of the Rear Exhaust/Muffler.

(The one that sits up in the cut out at the side of the Car)

There is a Rubber Grommet which needs to be removed.

Underneath which you will then see a Tap with a little spout on it, to which you could attach a tube 'IF' you wanted to.

Turning this Tap will then allow you to drain off the Fuel, before you remove the Sump Tank for more thorough Cleaning.

The only real PIA with this, is that you may find that the Tap does not line up with the hole, in which case you would then need to loosen or maybe remove some bolts

from the Sump Tank. To 'Jiggle it' into position, so that you can undo the Tap.



Remove the Grommet from this Hole to get to the Tap on the Sump Tank in order to drain it.



Once the Grommet has been removed, you will see this Tap to drain the Sump Tank.

 

Adding to the list from my experience, and knowing nothing of what has been done to that car.

1) The 1/2" hose that supplies fuel FROM the main tank TO that sump tank does collapse on the inside (age related), and that reduces supply of fuel.

If the pump cannot get a good supply TO it, a screaming noise is standard.

2), Along the underside of the car on the RH side is a steel pipe. This is the fuel SUPPLY pipe TO the engine bay. It runs VERY close to the front and rear jacking points, and I have had/seen many with this pipe crushed/damaged by silly people jacking the car in ignorance.

Pump cannot supply what it needs, so it screams, and the engine will NOT rev.

3) On the LH side of the underside of the car is a duplicate of the RH Supply pipe, it is the RETURN pipe to the tank. Suffers the SAME damage fate as the other side, and that will cause "over fueling" coz the unused fuel cannot return to that tank, so rail pressure simply goes thru the roof. I doubt you have this scenario, coz Black/.Grey smoke is the dead giveaway.

4) The pumps can be a tad noisy, but Bosch are not known for that. Ensure the pump is PROPERLY mounted in its clamp, with the foam insulation material PROPERLY fitted. If the pump makes metal contact with the clamp casing/battery cradle steel work, all sorts of weird noises will be heard.

Thats enough for now.

Lets know what you find, so we can keep adding.

 

My pump is a Bosch pump as well. Did the work myself, and bungled my way to victory. Mine whines after most trips, but has since the day I installed it. Haven't cleaned the sump tank, but it's on my to-do list.

The performance you are describing is similar to some of my own recent experiences. I had a hard time getting the car to run at highway speeds for a couple weeks over the winter, and found that both fuel pressure regulators had gone bad and needed to be replaced. That solved that problem.

 

I have actually drained the fuel tank and the small auxiliary tank (or whatever it is called - it was full of dirt). Now I am actually wondering if the mechanic put the fuel filter in the wrong way - it has the rounded end towards the side of the car, and the flat en towards the fuel pump. Will try to rotate 180 degrees, and see if that helps.

Also had a suggestion by a long time Jag mechanic at a car show Saturday; It may have something to do with the (unfortunate) US-spec downpipes with catalysts. Or it could be a problem with the cooling of the fuel pipe (don't know how the latter is accomplished to be honest). Or it could be the fuel pressure regulator. So, if rotating the fuel filter doesn't help, I'm buying a new regulator.

Cheers

//Ronnie

 

Virtually all F.I. fuel filters have an arrow showing direction of flow.....although it doesn't take much to inadvertently wipe away the ink. A bit of gasoline on your fingers and the markings disappear.


Take a peek before removing anything. You might get lucky and save yourself a bit of work....and spilled gasoline


Cheers
DD

 

Thanks Doug; the arrow on the filter shows that the flow goes from left to right - seen from behind.
If that is the correct position, then it must have something to do with the fuel pressure regulators.
Also checked underneath; no fuel lines seem to be damaged.

 

The filter is the right way round in the photo PROVIDED the fuel pump is connected to the LEFT HAND end in the photo.


Also, did you renew the sock filter inside the sump tank and blow out the fuel lines to the pump, filter and engine fuel rail inlet?

 

Hi Greg,
Yes, I did change the sump filter and made sure to clean alle tubes/hoses connected to the fuel pump.

It's quite a mystery.
I may dismantle the whole thing again next week, for lack of anything better to check.
Very thankful for all the tips I've bee receiving, from far and (relatively) near

 

So, I took everything out, sump tank, fileter etc; made sure it was all clean (it was already, but nevertheless), put everything back together, and took the car for a spin. Now the engine at least receives enough fuel, the kick-down even works, and she goes to well beyond 100 mph
However, the pump still whines. I've decided it just "German quality", and to live with it until I can find a proper UK-made pump!

Thanks for all the tips and help

Cheers

//Ronnie

 

Whilst you can normally hear the pump, boot lid open, if it is still really whining, you still have a supply problem or a duff filter, even if new.
I suggest you renew the feed pipe from the main tank to the sump tank, if you have not done so already. This is just a normal 1/2 inch fuel pipe not under any pressure apart from gravity.
If this does nothing, renew the filter even if new. Brand new filters can block themselves and stress the pump. Finally, if you loosen the filler cap, does the pump whining go after a minute or two? You might have a breather problem.

 

My pump is pretty noisy as well, but I believe it supplies the fuel as it should.

I had an 'incident' 6-8 weeks ago, where I filled 15 liter diesel in the tank. I emptied the resulting 30 liter of half'n'half fuel by disconnecting the fuel line in the engine bay and letting the pump do the work in the 3-second primings it does every time ignition is turned on. It took 240 turns of the key...
Funny thing is that my pump became absolutely quiet when the tank was empty. I actually thought it stopped working...

I will suggest you to disconnect the fuel line same way and measure how much fuel is delivered. It's quite easy to do.
I didn't measure it exactly, but I got around 0,1 liter in each priming. I'm sure someone else will know a more exact figure.