Octavia won't start (sometimes)

Hello,

I have a problem that my octavia sometimes won't start (1.8 20V SLX (AGN) 1997.)

It seams like fuel pump don't work well.

I test fuel pump on my desk and it pumps fuel as expected, I change fuel pump relay but the problem is the same.

With instrument I measured 2V when key is in the start lock, and 12V while starting the engine. The fuses are checked and replaced.

Immobilizer is working well.

I noticed this problem when the car is cold, but when it's started once, it will start again.

Could You help me please?

BTW:

I could not check the fault codes because I change my laptop and the new one don't have serial port :(

My doubt is fuel filter (didn' replace it for a 20 000 km) or some other electronics?

Thanks

Edited 9 September, 201015 yr by mskomersic