RE: '88 325iX Cold weather start problem - fuel regulator?

["Fadeev, Alex" <alex.fadeev@xxxxxxxxxxx>]

Dave Rathnow [mailto:Dave.Rathnow@domain.elided] wrote:
> 
> I left the car outside all day yesterday, in about -20C (no 
> plugs availalbe for block heater.)  When I tried to start it, 
> it would start, run for a couple of seconds and then died 
> immediately.  This went on for a few minutes until I started
> pumping the gas after it started.  It finally idled but was
> belching black smoke out the tail pipe and running really 
> rough. I could also smell lots of unburnt fuel.

Dave, 
Your engine was flooded. Either because the injectors where leaking while
the car was sitting (cold weather related?) or because of one too many
failed attempts to start the car. Each time you try to cold start the car
injectors fire for exactly 1 second to enrich the mixture for a cold start.
Do it too many times and the cylinder will get flooded.
Pressing the gas pedal does not effect fuel delivery. It opens the throttle
so that more air gets fed into the cylinders. The DME reacts to more air by
providing more fuel, etc, etc. Therefore, by pumping the gas pedal you
finally provided enough air for the combustion to commence and the engine
eventually fired, though it ran really rich for a while resulting in the
black smoke and the smell of gas coming out of the tail pipe.

> After I started driving, everytime I took my foot of the gas, 
> the engine stalled.  I also noticed that the fuel consumption 
> was about double what it normally should be. 

How did you notice that?

> Pretty soon, the engine light came on an stayed on. I 
> managed to make it home and plugged it in over night.

Let's start by figuring out _what_ engine light you got:
chapter 7.1.8 in BMW FAQ: 
http://www.unofficialbmw.com/~dalus/bmw/ftp/bmw/FAQ.7

Chance are, it will be related to running rich (O2 sensor? fuel pressure
regulator?) or indicative of some sensor failure causing rich mixture
condition (temp sensor?).

> When I went to start it this morning, it started and ran 
> fine, almost like nothing had happened.  Unfortunately, the 
> engine light is still on and, 

The light will stay on for something like 50 starts and if the condition
that originally set the light does not repeat it will extinguish. Or the
could be reset.

> while there is no black smoke 
> coming out of the tail pipe, I get a really strong smell of
> fuel in passanger compartment when I come to a stop <;o(

still running rich?

> Anybody hazard a guess as to what broke and what caused it to 
> break?  I'm thinking it could be my fuel regulator but I'm not sure.

Good thinking. I once had the fuel pressure regulator on my '89 325i go
weird on me and pump the injectors at much higher pressure then normal. Come
to think of it was in the middle of a winter. The engine would attempt to
start, stumble and die. The cylinder and plugs were bathing in gas. I drove
to the dealer in another car, bough a spare regulator only to discover that
the old FPU went back to normal. After a month without further FPU problems
I returned the new unopened FPU back to the dealer and never had this
problem again. Go figure.

good luck,
alex f

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