Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

 

Hi Graham,

What year is your A6?

A no start scenario could be the hall sender but that would thro a 2113
code. If it's the immobiliser, check for a faulty relay. I have a C4 S6 and
relay may be behind panel under steering column.

Tony

<graham@smith-hewerdine.freeserve.co.uk> wrote in message
news:1119813240.095083.86030@g14g2000cwa.googlegro ups.com...
Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

 

Hi Graham,

What year is your A6?

A no start scenario could be the hall sender but that would thro a 2113
code. If it's the immobiliser, check for a faulty relay. I have a C4 S6 and
relay may be behind panel under steering column.

Tony

<graham@smith-hewerdine.freeserve.co.uk> wrote in message
news:1119813240.095083.86030@g14g2000cwa.googlegro ups.com...
Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

 

Hi Graham,

What year is your A6?

A no start scenario could be the hall sender but that would thro a 2113
code. If it's the immobiliser, check for a faulty relay. I have a C4 S6 and
relay may be behind panel under steering column.

Tony

<graham@smith-hewerdine.freeserve.co.uk> wrote in message
news:1119813240.095083.86030@g14g2000cwa.googlegro ups.com...
Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

 

Hi Graham,

What year is your A6?

A no start scenario could be the hall sender but that would thro a 2113
code. If it's the immobiliser, check for a faulty relay. I have a C4 S6 and
relay may be behind panel under steering column.

Tony

<graham@smith-hewerdine.freeserve.co.uk> wrote in message
news:1119813240.095083.86030@g14g2000cwa.googlegro ups.com...
Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

 

graham@smith-hewerdine.freeserve.co.uk writes:

> Some time ago I posted about my A6 2.4 Auto that has an intermittent
> starting problem (details below). Since then, my garage (an independent
> Audi specialist) has checked over all of the obvious things (spark
> plus, cleaned the injectors etc), however the problem persists and next
> week the car is booked in with them to have the fuel pump replaced -
> purely on a speculative basis.

A bad fuel pump will give the problems you describe. Try and listen for
excessive noise from the fuel pump. It should not sound like a hive of
wasps in your fueltank.

The shop should be able to diagnose the fuel pump without replacing it by
measuring the pressure of the fuel pump before the filter. Low or too
low pressure will indicate a bad fuel pump.

On my '93 Audi 100 2.3E the pressure should be as high as 6.1 bar. I've
just replaced the fuel pump myself on mine. The shop had the pump gauged
to 2 bar... needless to say: The car wouldn't start.

Before I changed the filter it took it out of the tank and dropped it
into a bucket of water and applied power on the pump. A 2 foot column of
water shot straight in the air, but the water was black as soot. So got
some fresh water twice and gave the pump a good clean. I left the pump
to dry and replaced the fuel filter. I then reinstalled the fuel pump
and tried to start the car. It roared into life immediately.

Albeit, as the fuel pump had excessive noise I replaced it with a new.

A clogged fuel filter is a sure death for a fuel pump, and a change
should always be included in the 30k km service. It's cheap and it's
easy to do. So remember to change the fuel filter if you get a new fuel
pump installed. Otherwise your new fuel pump will have a short and
pointless life.

Just to get an indication of much crap there is in the fuel, try and
empty the content of the fuel filter into a clear bottle...

--
azoth@dod.no
------------------------------------------------------------------------
Wenn im Zweifel, Volleistung! DoD#2101
'93 Audi 100 2.3E When in doubt, floor it!

 

graham@smith-hewerdine.freeserve.co.uk writes:

> Some time ago I posted about my A6 2.4 Auto that has an intermittent
> starting problem (details below). Since then, my garage (an independent
> Audi specialist) has checked over all of the obvious things (spark
> plus, cleaned the injectors etc), however the problem persists and next
> week the car is booked in with them to have the fuel pump replaced -
> purely on a speculative basis.

A bad fuel pump will give the problems you describe. Try and listen for
excessive noise from the fuel pump. It should not sound like a hive of
wasps in your fueltank.

The shop should be able to diagnose the fuel pump without replacing it by
measuring the pressure of the fuel pump before the filter. Low or too
low pressure will indicate a bad fuel pump.

On my '93 Audi 100 2.3E the pressure should be as high as 6.1 bar. I've
just replaced the fuel pump myself on mine. The shop had the pump gauged
to 2 bar... needless to say: The car wouldn't start.

Before I changed the filter it took it out of the tank and dropped it
into a bucket of water and applied power on the pump. A 2 foot column of
water shot straight in the air, but the water was black as soot. So got
some fresh water twice and gave the pump a good clean. I left the pump
to dry and replaced the fuel filter. I then reinstalled the fuel pump
and tried to start the car. It roared into life immediately.

Albeit, as the fuel pump had excessive noise I replaced it with a new.

A clogged fuel filter is a sure death for a fuel pump, and a change
should always be included in the 30k km service. It's cheap and it's
easy to do. So remember to change the fuel filter if you get a new fuel
pump installed. Otherwise your new fuel pump will have a short and
pointless life.

Just to get an indication of much crap there is in the fuel, try and
empty the content of the fuel filter into a clear bottle...

--
azoth@dod.no
------------------------------------------------------------------------
Wenn im Zweifel, Volleistung! DoD#2101
'93 Audi 100 2.3E When in doubt, floor it!

 

graham@smith-hewerdine.freeserve.co.uk writes:

> Some time ago I posted about my A6 2.4 Auto that has an intermittent
> starting problem (details below). Since then, my garage (an independent
> Audi specialist) has checked over all of the obvious things (spark
> plus, cleaned the injectors etc), however the problem persists and next
> week the car is booked in with them to have the fuel pump replaced -
> purely on a speculative basis.

A bad fuel pump will give the problems you describe. Try and listen for
excessive noise from the fuel pump. It should not sound like a hive of
wasps in your fueltank.

The shop should be able to diagnose the fuel pump without replacing it by
measuring the pressure of the fuel pump before the filter. Low or too
low pressure will indicate a bad fuel pump.

On my '93 Audi 100 2.3E the pressure should be as high as 6.1 bar. I've
just replaced the fuel pump myself on mine. The shop had the pump gauged
to 2 bar... needless to say: The car wouldn't start.

Before I changed the filter it took it out of the tank and dropped it
into a bucket of water and applied power on the pump. A 2 foot column of
water shot straight in the air, but the water was black as soot. So got
some fresh water twice and gave the pump a good clean. I left the pump
to dry and replaced the fuel filter. I then reinstalled the fuel pump
and tried to start the car. It roared into life immediately.

Albeit, as the fuel pump had excessive noise I replaced it with a new.

A clogged fuel filter is a sure death for a fuel pump, and a change
should always be included in the 30k km service. It's cheap and it's
easy to do. So remember to change the fuel filter if you get a new fuel
pump installed. Otherwise your new fuel pump will have a short and
pointless life.

Just to get an indication of much crap there is in the fuel, try and
empty the content of the fuel filter into a clear bottle...

--
azoth@dod.no
------------------------------------------------------------------------
Wenn im Zweifel, Volleistung! DoD#2101
'93 Audi 100 2.3E When in doubt, floor it!

 

graham@smith-hewerdine.freeserve.co.uk writes:

> Some time ago I posted about my A6 2.4 Auto that has an intermittent
> starting problem (details below). Since then, my garage (an independent
> Audi specialist) has checked over all of the obvious things (spark
> plus, cleaned the injectors etc), however the problem persists and next
> week the car is booked in with them to have the fuel pump replaced -
> purely on a speculative basis.

A bad fuel pump will give the problems you describe. Try and listen for
excessive noise from the fuel pump. It should not sound like a hive of
wasps in your fueltank.

The shop should be able to diagnose the fuel pump without replacing it by
measuring the pressure of the fuel pump before the filter. Low or too
low pressure will indicate a bad fuel pump.

On my '93 Audi 100 2.3E the pressure should be as high as 6.1 bar. I've
just replaced the fuel pump myself on mine. The shop had the pump gauged
to 2 bar... needless to say: The car wouldn't start.

Before I changed the filter it took it out of the tank and dropped it
into a bucket of water and applied power on the pump. A 2 foot column of
water shot straight in the air, but the water was black as soot. So got
some fresh water twice and gave the pump a good clean. I left the pump
to dry and replaced the fuel filter. I then reinstalled the fuel pump
and tried to start the car. It roared into life immediately.

Albeit, as the fuel pump had excessive noise I replaced it with a new.

A clogged fuel filter is a sure death for a fuel pump, and a change
should always be included in the 30k km service. It's cheap and it's
easy to do. So remember to change the fuel filter if you get a new fuel
pump installed. Otherwise your new fuel pump will have a short and
pointless life.

Just to get an indication of much crap there is in the fuel, try and
empty the content of the fuel filter into a clear bottle...

--
azoth@dod.no
------------------------------------------------------------------------
Wenn im Zweifel, Volleistung! DoD#2101
'93 Audi 100 2.3E When in doubt, floor it!

 

Thanks for your replies! My A6 is a 1998, and there are no fault codes
being logged. I've just heard back from the A6 owner who had a similar
starting problem that turned out to be the immobiliser, and his car
didn't log any fault codes nor did the dashboard immobiliser light stay
illuminated. So immobiliser is still in the frame - or the relay
(thanks Tony).

BBO, if the fuel pump is the culprit, is it plausible that there would
only be a problem at startup? I'd have thought that the car might
suffer from other problems - poor running perhaps?

Cheers - Graham