1989 xj40 stalls out on hot days after during long drives...

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Bongo Fury - 26 Aug 2004 23:57 GMT
My cat's seemed to have developed a problem.
When I do on extended drives over 4 hours long,on hot sunny days she
just stalls out like I'm out of gas,however there is still over half a
tank on board.
It was suggested by a 'jaguar specialist' assured me it's the fuel
pump & filter,well $300 later and the problem consist.
Now it's been suggested that it may be a small crack in the Ignition
coil.Has anyone heard of this and could it be a possiblity?
Thanks to all who help and love the greaest motoring machine in the
world.
jim

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toppie - 27 Aug 2004 12:28 GMT
> My cat's seemed to have developed a problem.
> When I do on extended drives over 4 hours long,on hot sunny days she
[quoted text clipped - 7 lines]
> world.
> jim

I'm not a specialist on the XJ40 but it looks like a well-known problem.
Have you removed heat-shields from the engine or have you put insulation
under the bonnet leading to overheating the fuel-lines? Is it correct that
after cooling down everything is OK?
In that case, try driving for a testperiod, which normally causes stalling,
with the bonnet opened up. That worked for my old cars that had a problem
with it.
Fred

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peter williams - 02 Sep 2004 21:08 GMT
check fuel fault 44...oxygen sensor....peter j

> My cat's seemed to have developed a problem.
> When I do on extended drives over 4 hours long,on hot sunny days she
[quoted text clipped - 7 lines]
> world.
> jim
Reply to this Message

John M Shedlock - 21 Oct 2004 21:28 GMT
The fuel pressure regulator at the end of the fuel rail is subjected to heat
expansion and fuel pressures get inadequate at idle. I learned a hard
lesson to get this knowledge. My 1988 XJ6 VDP had the same dilemma when
coming to a stop and the engine dropped to idle speed. I followed the
advice of the Haynes automotive manuals suggestion to install a second fuelpump.

I piped it into the blank fitting on the front of the fuel rail. Two
weeks later an overpressurized fuel line burst while I was driving on
Interstate 95 and sprayed raw gas into the engine compartment and
ignited an engine fire which destroyed the car in minutes after the line burst.

Just as you have experienced, even the experts didn't see this one coming.
I've handbuilt custom intakes and fuel systems for carbureted, injected,
turbo-charged and superchaged engines for classic 6 cylinder Chevy's and a
couple of 70's era Kawasaki 4 cylinder superbike motors and I've never came
across a fuel delivery system as complicated as the on the 1988 Jag that
burned or my current cat, an '89 XJ6.

Do you hear what sounds like a
tapping rhythm a bad valve lifter would make, somewhere near the firewall
when you come to a stop and are at idle? You can only hear it when your
inside the car. The sound is similar to "water hammer" in a piping system
when you shut off a valve in a system without a damping standpipe. Same
thing is happening to the fuel pressure regulator. When the injectors click
shut, a good regulator will absorb the back pressure created in the fuel
delivery cycle without losing synchronization to the ignition timing. When
the diaphragm in the regulator expands from heat or ages, the regulator
loses synchronization at high fuel pressures which occur at idle.

Once the
engine load is off idle, the fuel back pressure drops dramatically to supply
the now hungry injector flow and the regulator functions adequately. That
explains the "experts" suggestion to find an ignition timing fault. The CPU
controls injector timing based on feedback from the ignition sensors and
fuel pressure sensors. The back pressure leak through the regulator changes
the fuel delivery volume and the now fuel delivery volume tells the CPU a
false value and it corrects with an ignition timing adjustment and the fuel
pressure at idle is inadequate to open the injectors.

Sort of like a leaky
heart valve in a human. This is what I believe caused the burst fuel line in
my '88. I was at highway speed, (for my '88 that was usually between 85
and 105mph) I let off the accelerator and an instantaneous but brief
backpressure in the fuel lines from the air flow snapping shut, told the
CPU to reduce injector flow. At that instant both fuel pumps were
delivering high volumes through the regulator and the backpressure leak
blew the dual pumped fuel rail line.

Have you ever seen a "top fuel" nitro car
blow a supercharger off the engine on a burnout? Same physics here. Bad
fuel delivery timing and back pressure into the fuel lines. Nitro burners
react violently to lean fuel to air ratios !!!


> My cat's seemed to have developed a problem.
> When I do on extended drives over 4 hours long,on hot sunny days she
[quoted text clipped - 7 lines]
> world.
> jim
Reply to this Message
Nick - 21 Oct 2004 23:51 GMT
Possible reason for the knocking sound is because the in-line damper is in
need of replacing (disc shaped object in engine bay near fuel rail with
inlet and outlet hose for fuel).

Another possible likely reason it stalls is because there is no fuel cooler
in the delivery side if the fuel line as there is with the series I - series
III cars (4.2L 6's and 5.3 V12's). You can retrofit one from an xjs v12.

I would hardly call this fuel system complicated?! 6 Injectors, 1 regulator,
2 dampers, a delivery and return line, a pump, a coolant temp sensor, a
MAF meter and an ECU. All pretty standard stuff.

HTH (these are direct fixes to actual problems I have encountered in the
trade)

Cheers
Nick


> The fuel pressure regulator at the end of the fuel rail is subjected to
> heat
[quoted text clipped - 66 lines]
>> world.
>> jim
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Bongo Fury - 12 Dec 2004 23:39 GMT
Since my original post,
I have replaced the coil,which seems to have taken care of the
problem,,,,well so I thought,Went on a drive to Indianapolis on Oct
29,only to have the engine stall out again on me,this time though
there was no restarting it because upon closer inspection I discovered
that the valve cover gasket had given out and allowed oil to
accumulate around the spark plugs and basically drown them in oil so the
spark was gone.Now that I've replaced the gasket,everything's been
running great.....well except for the little ******* that put a
screwdriver into the oil cooler las month,I've never seen so much oil
in my life.I was actually afraid the EPA was goin' to bust me.
So after another $575.15 fix I happy to say I'm back on the
road.hoping to find the little vandal and possibly make the human gene
pool a little cleaner....

Happy driving to all

jim


>Possible reason for the knocking sound is because the in-line damper is in
>need of replacing (disc shaped object in engine bay near fuel rail with
[quoted text clipped - 84 lines]
>>> world.
>>> jim
Reply to this Message
webserve - 13 Dec 2004 00:59 GMT
Actually, The FIRST person you should be going after is the guy who
charged you $575 to fix the oil cooler. They list NEW for $120 to $136.12
(Part #CAC8509) -- used they are about $50. Sad how some Jag owners continue to insist upon being ripped off!!

Cheers
Webserve


> Since my original post,
> I have replaced the coil,which seems to have taken care of the
[quoted text clipped - 103 lines]
> >>> world.
> >>> jim

 

You have an external fuel pump IIRC. These pumps can have a vapor lock/overheat problem on hot days. Happens to me now and then on hot days here in NM. Jaguars official fix is to have two fuel pumps and run them in parallel.

This job is work and $ so my fix: wrap your fuel rail in reflective material. Tin foil worked great for me. Ensure all temp sensors and sendings units are operative and your mechanical fan clutch is operating. After the tin foil trick it cut 75% of my problem. Also keep your fuel tank full, I have found that works as well. Otherwise jaguar says "a short cool down period fixes it" this is true.

The fuel cooler is a good idea as well.

 

The kick I got out of this thread was that the solution to the man's problem of his XJ40 stalling on hot days after long drives was

• a coil replacement ... and
• a leaking valve cover repair.

Out of the much advice given:

I like Fred's idea about driving with the bonnet popped for test purposes.

I am now not so sure about advising anyone to install twin fuel pumps, even if Jaguar recommends it. Jaguar has had other models that had a propensity to catch fire in the engine bay. Ob there is risk involved and it may be a good idea to carry a fire extinguisher if you decide to do the installation.

Yeah, I suggested in another thread about wrapping the fuel lines with insulation, keeping the tank full and maybe adding a fuel cooler.

There is another Jaguar model that can be cannibalized for a fuel cooler and I posted that info on another thread, too.

I have some info I found about a fuel cooler but not for Jaguar. It will have to be modified to fit into the LOW pressure return line.

I'll post that in the near future.

 

I have a similar problem. My 1990 Sovereign 4.0 stalls when I come to a stop. I have to put the transmission into neutral to avoid stalling. (Note: The transmission cable is frayed and out of adjustment. Would that have anything to do with it?) My mechanic told me that the Idle Control valve next to the injectors might need cleaning. I removed that and replaced it with another I had scrubbed with a tooth brush and carb cleaner, but it still stalls. Any ideas?

 

Assuming the IAC is working properly my next guess in the mechanical area might be the fuel pressure regulator. You might try and open up the IAC air bypass screw a turn or two and see if that helps. Note exacly how much you turn it though so you can reset it. Otherwise refer back to Idle setting procedure...

Although it could be something out of adjustment in the A/t but I couldn't tell you what.