[xj40] Fuel Fail 29

XJ40
1

Hi all,
Bad week for Jag’s in Central CA. While on the way home
to let me know that the A/C wasn’t working, the Jag Coughed and
stumbled and stuttered. Ended up with a Fuel Fail 29 Fault code
and the Check engine light was lit. ECU failure is pretty vauge.
Can anyone tell me what cured their FF29? I was a thinking that
the CPS hasn’t been renewed on this car that I am aware of. I hate
to just throw parts at it though.

Thanks again for any advice! Thanks Double for good advice!–
Thanks int3man Michael :slight_smile: Roz’s toy 1991 SOVEREIGN 4.0
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2

In reply to a message from Roz’s Toy Mechanic sent Sat 20 Aug 2005:

Michael,

FF29 is flagged if the engine management system (EMS) self-test
fails. That self-test occurs each time you switch on the ignition.
If there is a ‘glitch’ in the data stored in the system, then FF29
will be flagged.

Usually that is caused by things like low battery volts or poor
power or ground connections at the EMS ECU and the ‘fix’ is to
remove both the yellow and blue connectors at the ECU, check for /
clean corrosion on the pins and spray with contact cleaner. When
you reconnect and clear the computer memory (remove instrument fuse
#5 or #6 in centre fuse box with ignition on, wait a while, re-
insert fuse etc) the ‘Check engine’ light should extinguish when
you start the engine.

If not, let me know - I’ve found some further checks that can be
done on the ECU electrics.

[PS, Don’t think it can be anything to do with the CPS, but if it’s
original, not a bad idea to change it out anyway :-)]–
The original message included these comments:

      Bad week for Jag's in Central CA.  While on the way home

to let me know that the A/C wasn’t working, the Jag Coughed and
stumbled and stuttered. Ended up with a Fuel Fail 29 Fault code
and the Check engine light was lit. ECU failure is pretty vauge.
Can anyone tell me what cured their FF29? I was a thinking that
the CPS hasn’t been renewed on this car that I am aware of. I hate
to just throw parts at it though.

–
Bryan N, '91 Sovereign 4.0 L, (RHD)
Cambridge, United Kingdom
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3

In reply to a message from Roz’s Toy Mechanic sent Sat 20 Aug 2005:

Try the cheap fix first swap relays on firewall dont forget relay
in trunk every time you turn key on you should hear fuel pump run
for a couple of seconds–
If you love it set it free if it returns it needs money
missouri, United States
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4

In reply to a message from Big Galoot sent Sun 21 Aug 2005:

There aren’t any relays on the firewall on a '91 car and on that
model, the fuel pump relay is in the engine bay next to the brake
pedal housing on LHD cars - it gives the pump its half-second
priming burst each time the ignition is switched on.–
The original message included these comments:

Try the cheap fix first swap relays on firewall dont forget relay
in trunk every time you turn key on you should hear fuel pump run
for a couple of seconds

–
Bryan N, '91 Sovereign 4.0 L, (RHD)
Cambridge, United Kingdom
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5

In reply to a message from Bryan N sent Sun 21 Aug 2005:

Fixed it Fuel fail 29. Had to disconnect the battery to get the
code to clear. It cleared and stayed gone. I’ll get to the CPS
next time I order parts.

Thanks for the assistance. I’m on to the A/C compressor now.

I have a jumper wire next to the Fuel pump relay. You just never
know when you are going to have to jumper that puppy.

Thanks for all the assistance.–
Thanks int3man Michael :slight_smile: Roz’s toy 1991 SOVEREIGN 4.0
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6

Well, after a number of years of very reliable running,
Ferguson really through a tantrum today.

First symptoms appeared as a miss at idle and the feeling of
reduced performance.

Heading home from dinner, lost all power and the engine quit
before I could get the car fully off the road.

Restarted OK, seemed fine idling in a parking lot but when I
tried to exit the lot, again lost all power but maintained a
very poor idle.

Just as I started to reach for the Auto Club card and cell
phone (thinking fuel pump at this point), the Check Engine
light came on, idle returned to normal and Ferguson did not
miss a beat returning home.

The symptoms remind me very much of the OS sensor failure
I’d had years ago when the car would run fine when cold, but
would stumble and loose power as the ECU transitioned from
closed loop processing to open loop. Would finally trip FF
44, return to closed loop processing and run find till the
next restart/cool down.

Was surprised to see Fuel Fail 29 on the VCM and a search of
the archives really does not show all that many occurrences,
nor cures. Best suggested was from Brent G of years past
suggesting cleaning the ECU electrical connections and
battery connections. Will try that but am hoping for
additional (if available) information.

Has anyone found any causes/cures for FF 29? Heck! From the
archives, looks to be a very unusual failure. Has anyone
else even suffered such?

Thanks!–
91 XJ6, 93 Sov, 97 Sov – Driveway’s crowded!
Tampa Fl, United States
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7

In reply to a message from Win sent Sun 16 Mar 2008:

Win,

I assume that ‘Ferguson’ is your '93 car? If not, some of
the comments in here may not apply.

I produced this for someone a while ago - it may help you:-

DTC 29 trouble shooting guide

The ECM with the blue and yellow connectors is the
EMS engine control module.
That is the thing which is generating the FF29 code. If the
battery is good and the connections at the ECM are clean,
there must be another problem with the ECM or the wiring to it.

Here are the checks Jaguar recommend after checking that the
battery and the ECM connectors are OK:-

  • Switch ignition ON
  • Back probe individually ECM Yellow connector pin #1
    (White/brown wire), ECM Blue connector pins #10 (White/brown
    wire) and #22 (White/brown wire) and in each case accurately
    measure the voltage to ground.

? Is there battery voltage at each of those pins?
? Are the voltage measurements within 200mV of each other?

*If NO to either of the above questions, repair the ignition
switched power supply to the ECM.

[Obviously for that you will need the wiring diagrams for
your car since it becomes quite involved. I recommend the
JDHT CD-Rom JHM1130 which has the requisite diagrams for
your car. HOWEVER, I would first suspect the EMS Main Relay,
the one in the Black base of that group of six on the
firewall in the engine bay. If that relay is suspect, it
could also be the cause of your ‘misfire’ symptoms].

If the answer to the above questions is YES:-

  • Switch the ignition OFF
  • Back probe individually ECM Yellow connector pin #18
    (Black wire), ECM Blue connector pins #11 , #23 & #24 (all
    Black wires) and in each case measure the resistance to
    ground.

? Is there LESS than 1 Ohm resistance to ground at each pin?

If NO, you must find and repair the ECM grounds - one is
attached to the #3 inlet manifold, two are attached to the
bulkhead (firewall) behind the cylinder head.

If, after all of that and AFTER you have cleared the ECM
memory [disconnecting the negative battery lead for 30
seconds or removing the instrument pack fuse with the
ignition ON (but engine not running) for a few seconds], the
Check Engine light comes on and FF29 reappears when you
start the engine, Jaguar recommend that you REPLACE the ECM
! :-)–
The original message included these comments:

Ferguson really through a tantrum today.
First symptoms appeared as a miss at idle and the feeling of
reduced performance.
Was surprised to see Fuel Fail 29 on the VCM and a search of
the archives really does not show all that many occurrences,
Has anyone found any causes/cures for FF 29? Heck! From the
archives, looks to be a very unusual failure. Has anyone
else even suffered such?

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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8

In reply to a message from Bryan N sent Sun 16 Mar 2008:

Bryan,

My apologies, Ferguson is the '91, I cannot believe I
omitted that on my original post.

Still, other than a few locations, your very sage advice is
still applicable. Many thanks.

I do have a copy of JHM1126. Per chance, do you know the
differences?

With a few decades of experience in the IT industry, and
currently designing, implementing and troubleshooting
control systems for industrial refrigeration units, it pains
me to admit but, I’ve found the CD difficult to navigate,
and the wiring diagrams nearly impossible to read or follow.
Might DJHT have improved the usability of the informaion?

Thanks!

Win–
The original message included these comments:

I assume that ‘Ferguson’ is your '93 car? If not, some of
the comments in here may not apply.
I produced this for someone a while ago - it may help you:-
DTC 29 trouble shooting guide

–
91 XJ6, 93 Sov, 97 Sov – Driveway’s crowded!
Tampa Fl, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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9

In reply to a message from Win sent Sun 16 Mar 2008:

Win,

In all honesty, JHM 1126 for the most part is a waste of time.

The later Cd-Rom titles produced by Mark Greer, whilst not
perfect, are a huge improvement IMHO.

In particular though, JHM1130 is a ‘special’ in that it
contains some excellent supplementary information on all
sorts of things not included in the factory service manuals
or wiring diagrams, including a full section on diagnostic
procedures and codes, but primarily because for the full
range of XJ40s, it has circuit diagrams which are much
more user friendly - even I can understand them! :-).

The only caution is that those circuit diagrams are for US
LHD cars, so you need to be careful if you have a RHD car to
ensure that the differences between LH and RHD
configurations, harnesses and component locations are
understood.

Fortunately, the wiring colours / pin locations in that
write-up are equally applicable to the '91 model although I
believe the ‘high power’ connector on your '91 car ECM is
black, not blue, but the ‘low power’ connector should still
be yellow?

Of course, the Main EMS relay is not on the firewall on your
'91 car but the one in the red base on the component panel
under the passenger side dash and I believe the ground on
the manifold is on #2 inlet tract stud.–
The original message included these comments:

I do have a copy of JHM1126. Per chance, do you know the
differences?
Might DJHT have improved the usability of the informaion?

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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10

In reply to a message from Bryan N sent Sun 16 Mar 2008:

Bryan,

So maybe I’m not dumb after all. I’d been pleasantly
surprised at how much more ‘‘user friendly’’ my JHM1178 for
the X-300 was over JHM1126 for the XJ-40. Think I’ll
contact Julie at JDHT to get copy of JHM1130.

Before I go crawling around under the dash, I think I’ll
replace the Main EMS relay. After 17 years, 180K miles and
absolutely countless cycles I’m sure that relay has seen
better days. A quick, painless attempt to isolate the
problem before I spend some (already warm/hot) afternoons
under the dash tracing and troubleshooting.

Again, many thanks for your sage advice.–
The original message included these comments:

Win,
In all honesty, JHM 1126 for the most part is a waste of time.
The later Cd-Rom titles produced by Mark Greer, whilst not
perfect, are a huge improvement IMHO.

–
91 XJ6, 93 Sov, 97 Sov – Driveway’s crowded!
Tampa Fl, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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11

In reply to a message from Win sent Mon 17 Mar 2008:

Win,

See my previous post - the EMS Main relay is under the
dash on your '91.

You’ll have to sweat it out under there! :slight_smile:

[Speaking to my son in Orlando yesterday, whilst we were
cowering indoors here with cold, blustery, rainy weather, he
was boasting 82� on a sun lounger on his boat dock! - Grrr!]–
The original message included these comments:

Before I go crawling around under the dash, I think I’ll
replace the Main EMS relay. After 17 years, 180K miles and
absolutely countless cycles I’m sure that relay has seen
better days. A quick, painless attempt to isolate the
problem before I spend some (already warm/hot) afternoons
under the dash tracing and troubleshooting.

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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12

In reply to a message from Bryan N sent Mon 17 Mar 2008:

Bryan,

Yea, I know the EMS main relay is under the dash/glove box,
but swapping out the relay was much less of an exercise in
contorting the human body into the foot well than chasing
pin outs and wiring connections under there.

The good news, after swapping the relay, I’ve experienced no
further problems. Both the irregular miss in the engine and
the stall/poor idle problems appear cured (knock gently on
dash trim)

With the temps back up 85�f/30�c I did take the opportunity
to swap out the ECU for the climate control. At least so
far, the A/C not running when the car is first started after
a heat soaking in the sun is also gone. That’s one symptom
I surely won’t miss. Get the interior too hot and the A/C
quits??? Made no sense at all!

I’ve still a few things to get Ferguson fully ready for the
summer. Fluids, hoses and such but it’s nice to have my
confidence restored and have all 3 Jags back into ‘‘trusted’’
status.

Again Bryan, many thanks for your advice. As usual, your
sage insight (and copy of the ‘‘good’’ JDHT CD) was invaluable.–
The original message included these comments:

See my previous post - the EMS Main relay is under the
dash on your '91.
You’ll have to sweat it out under there! :slight_smile:

–
91 XJ6, 93 Sov, 97 Sov – Driveway’s crowded!
Tampa Fl, United States
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