1994 BMW 520 Auto - engine won't start properly

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Ste - 23 Aug 2006 16:10 GMT

Hi
Today after a about half a dozen short runs - it has been thrashed on
those runs too - my BMW is now refusing to start properly.

It does crank, and can just about sustain itself at low revs (i.e.
below the normal idle) for about 5 seconds before it starts to struggle
further and then revs gradually drop until it stalls. Any pressure on
the accelerator stalls the engine immediately.

I'm not sure whether it's relevant, but there has been an intermittent
fuel smell from the car since I've had it (a few months). Economy has
consistently left something to be desired. In the last few days
however, economy seems to have hit rock bottom and there has been a
persistent smell of fuel both inside the car while driving, and outside
the car after parking up.

My guess is that it's something related to the fuel system, but can
anyone confirm what the exact problem(s) could be?

Reply to this Message

R. Mark Clayton - 23 Aug 2006 17:23 GMT

> Hi
> Today after a about half a dozen short runs - it has been thrashed on
[quoted text clipped - 14 lines]
> My guess is that it's something related to the fuel system, but can
> anyone confirm what the exact problem(s) could be?

Look for a potato that some kid has stuffed up the exhaust.

Reply to this Message

Enoch Root - 27 Aug 2006 17:30 GMT

Hi,

The Idle Control Valve(ICV) gets dirty and needs to be cleaned or
replaced. Next in line is the Mass Air Flow meter(MAF). Then after that
are the 02 sensors. And next is the ignition coils and their spark plug
counterparts. www.bmaparts.com or www.bavauto.com for your parts- try to
get OEM where possible.

So, those are the steps to fixing whats wrong, but it's just a guess. You
need to get the error codes from the ECU read by a code reader. Either
your BMW CCA club will have a reader you can borrow or a BMW independent
mechanic can read it for you. Don't go to a BMW dealer for this. You are
in a perfect position to get screwed with your issue. Best of Luck.

ER

Reply to this Message

Ste - 27 Aug 2006 19:24 GMT

> > Hi
> > Today after a about half a dozen short runs - it has been thrashed on
[quoted text clipped - 30 lines]
>
> ER

Thanks for your suggestions. On further investigation, it seems there
is no power to the fuel pump - either with the ignition turned on, or
while actually cranking the engine.

>From a logical point of view, I imagine that rules out the ICV, the O2

sensors, and the spark plugs.

I'm also under the impression that fuel pumps are supposed to start up
momentarily when you turn the ignition on (before cranking the engine),
in expectation of starting the engine. As I say, there is no power
whatsoever to the fuel pump under any circumstance, so do I also assume
that the MAF is ruled out? If not, how might I go about establishing
whether the MAF is working?

It also seems to me that the problem is more likely than not
electrical. I've checked the relevant fuses. I'm also under the
impression there are various relays that may need to be checked, but
I'm unable to identify the relevant relays nor find information on how
I might be able to check their functioning.

If you'd be able to help me any further on these questions I'd be very
grateful.

Reply to this Message

Floyd Rogers - 27 Aug 2006 19:47 GMT

> Enoch Root wrote:

> Thanks for your suggestions. On further investigation, it seems there
> is no power to the fuel pump - either with the ignition turned on, or
> while actually cranking the engine.

Fuel pump relay. Not sure where it is in a 520i right hand drive.

FloydR

Reply to this Message

Ste - 30 Aug 2006 19:51 GMT

> > Enoch Root wrote:
>
[quoted text clipped - 5 lines]
>
> FloydR

As I said, I'm not aware of the location of the relay, nor how to test
the relay if indeed I was able to find it. Surely someone here must
know...

Reply to this Message