Weird starting issue.

[190E Matt]

Just a quick question,

When starting the Merc from stone dead cold, first turn of the key will have it fire up for about half a second, and then it will die. Crank it over again, and it just can't quite fire up, sort of stuttering. Wait about 10 seconds, try again and it fires up instantly.

Also if the car is warm and you turn the key to crank it over, it fires up pretty much instantly.

I am guessing it is something related to the fuel system, although I am probably wrong.

Any ideas?

Thanks,

Matt.

[andy-xr]

I'd be looking at changing the fuel filter as a first effort, assuming it's not had one for a while

If that checks out, possible blockages. I think you're right with fuelling, it's either that or spark I'd say

[bertelli_1]

fuel could be draining back to the tank overnight (fuel injection?).

[skid-mark]

could be faulty coolant temp sender not giving the car correct fueling from start up

[wingnut.]

Crank it over a couple of times then when it cuts out try clamping the return fuel hose, you might be loosing fuel pressure

[Pentoman]

The fuel pressure you could test a few ways... the supply line comes off easily or alternatively you can push the air flap (take off the top of the airbox) down. This has a resistance due to fuel pressure; when pressure is gone this thing goes really floppy and easy to move.
I doubt it's fuel pressure just because it doesn't seem common with these. Your problem however does seem.
Could it be a head gasket - leaking water into cylinders which means it doesn't run right for the first few seconds, until the water is cleared?
The coolant temp sensor is easy to test, it looks like this on a later model

but if an earlier model will be smaller and 2 prong but in the same general area... you'll figure it out.
Test with multimeter, figures should be 300-350 ohms at 80 deg
100-1400 ohms at 40 deg
~4000 ohms at 10 deg C
and so on

From experience I'd think if it the coolant temp sensor you'd get constant idling issues as opposed to just temporary. Also did you know you can run the car without the ECU and it will pretty much run perfectly? The computer stuff isn't all that important on these, strangely.

My replies aren't normally so comprehensive but I was looking at these yesterday...

Oh just had a thought could be leaking its fuel pressure out the EHA which looks like this (under the airbox)
and can leak itself or out of the o-rings sealing it in. Was it off and see if it starts to leak overnight I guess? I got a spare one + the seals from a scrappy for £2 but Merc would want more like £60-80.
bit if you remove the whole airbox it's a huge faff because the pipes come off underneath; if you don't connect them back up you'll really know about it it will idle terribly.