Diesel starting problem - update

Hi All

I'm not 100% sure of the netiquette associated with providing an update to a
recent thread. I'm sure, if you're like me, that you don't read old threads,
so I thought I'd make a posting under a new subject.

If you can recall, I have an old BMW that has an intermittent starting
problem. It is not frequent, but has happened again. I'm pretty sure now
that it relates to a less than 1/4 full tank. Certainly, in answer to
another poster, there is NO cloud of black smoke when it does start. This
would presumably indicate that no fuel is getting into the engine, and may
suggest a pump or filter problem.

The local garage could not identify a problem, but did notice that there was
a new fuel filter fitted. I guess this was at a BMW service (I'll ask them
next week). My FIL also noted that their BMW (diesel) had a similar starting
problem that had a fuel pump relay replaced as a first guess; later the
whole pump was replaced which cured the problem.

Would this problem suggest that the fuel filter or pump is at fault? Why
would a faulty pump only show up as faulty with an empty(ish) tank?

In message >, Grumps
> writes
>Hi All
>
>I'm not 100% sure of the netiquette associated with providing an update to a
>recent thread. I'm sure, if you're like me, that you don't read old threads,
>so I thought I'd make a posting under a new subject.

I'd always prefer a followup to the original thread, if I'd been
interested in the thread I'd have flagged it as interesting and it would
have appeared at the top of the threads list when the followup got
posted.

--
bof at bof dot me dot uk

"Grumps" > wrote in message
...
> Hi All
>
> I'm not 100% sure of the netiquette associated with providing an update to
> a recent thread. I'm sure, if you're like me, that you don't read old
> threads, so I thought I'd make a posting under a new subject.
>
Updates are always welcome, as far as I'm concerned.

> If you can recall, I have an old BMW that has an intermittent starting
> problem. It is not frequent, but has happened again. I'm pretty sure now
> that it relates to a less than 1/4 full tank. Certainly, in answer to
> another poster, there is NO cloud of black smoke when it does start. This
> would presumably indicate that no fuel is getting into the engine, and may
> suggest a pump or filter problem.
>
> The local garage could not identify a problem, but did notice that there
> was a new fuel filter fitted. I guess this was at a BMW service (I'll ask
> them next week). My FIL also noted that their BMW (diesel) had a similar
> starting problem that had a fuel pump relay replaced as a first guess;
> later the whole pump was replaced which cured the problem.
>
What's "FIL"?
Do you remember my message about the postal van which wouldn't start in the
morning, and on which a fuel _lift_ pump replacement cleared the fault?
By the way, the diaphragm is the usual culprit. If it's damaged (often not
easy to see) it lets air in. The 2 valves are usually trouble free. What I
mentioned about fuel filter sealing rubber rings, also applies to fuel lift
pump rubber rings. There are usually two of them; one large one which goes
at the bottom, and a small one which goes at the top.
You used to be able to get replacement diaphragms, but I don't know what the
position is now.

> Would this problem suggest that the fuel filter or pump is at fault? Why
> would a faulty pump only show up as faulty with an empty(ish) tank?
I'm not sure about your particular case; but I believe that the longer (in
length) the fuel pipe is to the fuel lift pump, the greater loading there is
on it. I can only _suggest_ that a low level of fuel in the fuel tank will
increase the actual length of the fuel line, and therefore increase the load
on the pump (it has to work harder).

If your BMW has done a high mileage, and the fuel lift pump is the original
one (as far as you know); then changing it could
be accepted as long term _maintenance_, and be an acceptable thing to do.
An example: An engine camshaft drive belt is usually recommended to be
changed at a certain mileage (60,000 miles comes to mind). It might run much
longer, but I would certainly change it as recommended, _for my peace of
mind_ if nothing else. A broken belt can/will do a lot of damage to pistons,
valves, and even connecting rods.

Sylvain.

>

Sylvain VAN DER WALDE wrote:
>>
> What's "FIL"?

Father-in-law

Grumps wrote:
> Hi All
> If you can recall, I have an old BMW that has an intermittent starting
> problem. It is not frequent, but has happened again. I'm pretty sure now
> that it relates to a less than 1/4 full tank. Certainly, in answer to
> another poster, there is NO cloud of black smoke when it does start. This
> would presumably indicate that no fuel is getting into the engine, and may
> suggest a pump or filter problem.
>
> The local garage could not identify a problem, but did notice that there was
> a new fuel filter fitted. I guess this was at a BMW service (I'll ask them
> next week). My FIL also noted that their BMW (diesel) had a similar starting
> problem that had a fuel pump relay replaced as a first guess; later the
> whole pump was replaced which cured the problem.
>
> Would this problem suggest that the fuel filter or pump is at fault? Why
> would a faulty pump only show up as faulty with an empty(ish) tank?
>
>
When the problem occurs try taking off the filler cap if a sucking sound
is heard then try starting the engine now, if that cures the problem
then that is your source right there, vacuum, 1mm hole in the cap
usually fixes the problem.

//J

Grumps wrote:
>
> If you can recall, I have an old BMW that has an intermittent starting problem.

How the hell are we supposed to recall this on a new thread, you dummy?

Is it diesel or petrol?

If petrol replace the condenser.

If that doesn't sort it, it might be the air vent to the tank; petrol
or diesel. Run the tank dry till the problem starts then remove the cap
to allow air into the tank. If that solves it, you need to clean the
filler cap or replace it.

If that isn't the problem, run the fuel tank as low as you can, then
empty it. If the tank has water in, you have found the problem.

While this does come under the remit of DIY, as with computer threads,
they aught to be posted to newsgroups better suited to the problem. But
of course the thing is, you are a dummy.

Weatherlawyer wrote:
> Grumps wrote:
>>
>> If you can recall, I have an old BMW that has an intermittent
>> starting problem.
>
> How the hell are we supposed to recall this on a new thread, you
> dummy?

Well, silly me. Sorry!

> Is it diesel or petrol?

Oh dear! I bet you wish you could crawl into a hole now. Did you read the
subject?

<snip mostly quite useful stuff>

Jan Larsen wrote:
> Grumps wrote:
>> Hi All
> > If you can recall, I have an old BMW that has an intermittent
> starting
>> problem. It is not frequent, but has happened again. I'm pretty sure
>> now that it relates to a less than 1/4 full tank. Certainly, in
>> answer to another poster, there is NO cloud of black smoke when it
>> does start. This would presumably indicate that no fuel is getting
>> into the engine, and may suggest a pump or filter problem.
>>
>> The local garage could not identify a problem, but did notice that
>> there was a new fuel filter fitted. I guess this was at a BMW
>> service (I'll ask them next week). My FIL also noted that their BMW
>> (diesel) had a similar starting problem that had a fuel pump relay
>> replaced as a first guess; later the whole pump was replaced which
>> cured the problem. Would this problem suggest that the fuel filter or
>> pump is at fault?
>> Why would a faulty pump only show up as faulty with an empty(ish)
>> tank?
> When the problem occurs try taking off the filler cap if a sucking
> sound is heard then try starting the engine now, if that cures the
> problem then that is your source right there, vacuum, 1mm hole in the
> cap usually fixes the problem.

Thanks for that (and to Silvain, yes I do remember your earlier comment).
I've had a listen at the tank. To me, it doesn't sound quite right. A sort
of gurgling, and screeching. Maybe this is what the fuel lift pump should
sound like. If I can get the car going this morning, I'll take it down to
our local garage again.
I can't understand why the engine runs properly when it is going though.

Grumps wrote:
> Weatherlawyer wrote:
>> Grumps wrote:
>>>
>>> If you can recall, I have an old BMW that has an intermittent
>>> starting problem.
>>
>> How the hell are we supposed to recall this on a new thread, you
>> dummy?
>
> Well, silly me. Sorry!
>
>> Is it diesel or petrol?
>
> Oh dear! I bet you wish you could crawl into a hole now. Did you read
> the subject?
>
> <snip mostly quite useful stuff>

LOL well done !

"Grumps" > wrote in message
...
> Jan Larsen wrote:
>> Grumps wrote:
>>> Hi All
>> > If you can recall, I have an old BMW that has an intermittent
>> starting
>>> problem. It is not frequent, but has happened again. I'm pretty sure
>>> now that it relates to a less than 1/4 full tank. Certainly, in
>>> answer to another poster, there is NO cloud of black smoke when it
>>> does start. This would presumably indicate that no fuel is getting
>>> into the engine, and may suggest a pump or filter problem.
>>>
>>> The local garage could not identify a problem, but did notice that
>>> there was a new fuel filter fitted. I guess this was at a BMW
>>> service (I'll ask them next week). My FIL also noted that their BMW
>>> (diesel) had a similar starting problem that had a fuel pump relay
>>> replaced as a first guess; later the whole pump was replaced which
>>> cured the problem. Would this problem suggest that the fuel filter or
>>> pump is at fault?
>>> Why would a faulty pump only show up as faulty with an empty(ish)
>>> tank?
>> When the problem occurs try taking off the filler cap if a sucking
>> sound is heard then try starting the engine now, if that cures the
>> problem then that is your source right there, vacuum, 1mm hole in the
>> cap usually fixes the problem.
>
> Thanks for that (and to Silvain, yes I do remember your earlier comment).
> I've had a listen at the tank. To me, it doesn't sound quite right. A sort
> of gurgling, and screeching. Maybe this is what the fuel lift pump should
> sound like. If I can get the car going this morning, I'll take it down to
> our local garage again.
> I can't understand why the engine runs properly when it is going though.
>
I had a faulty (genuine new BMW) lift pump fitted in my 525TDS and difficult
starting was its result.
I think it had no dip tube or it leaked slowly at the top, as it would only
start when the tank was
nearly full - i.e. was able to prime down to about 3/4 full.

I also fitted a set of new BERU glowplugs which weren't expensive but are
apparently good I later discovered.

Nick