After changing the fuel filter, engine changed sound, there are fuel and smoke out of tail pipe. Scan showed system max rich.

Where to start?

Fiat Punto 1995 1.2 75

Thanks in advance!

Find your fuel pressure regulator at end of fuel rail, remove the little rubber vacuum hose that is connected to inlet manifold vacuum.
Is there fuel in the rubber hose?

Did you do anything else while changing fuel filter?

With the rubber vacuum hose removed from fuel pressure regulating turn key to on(not start)
You should hear fuel pump run for a few seconds.
If fuel comes out of fuel pressure regulator where vacuum hose connects then pressure regulator is broken and you need a new one.

I have some more checks you can do but please do that one first and save me having to write everything.
Good luck.

Okay, tough 2 days for nothing. Let me explain what dumb things I've done.
First, I went to replace fuel filter, couldn't remove it, full of dirt and corrosion, had to cut it. Okay I removed it. Went to torque it, first nut okay, second one leaking. Changed washers (not sure if they'll called like that). Nope, not working. After dozen of tries seemed it will work, and then I realize my head is full of petrol from above. Went to fuel pump to investigate, one of connector pipes was broken (red things on pump picture). So, after dozen of tries I managed to improvise something and changed hose from plastic to rubber and found some old filter which seemed fine (new filter was leaking cause I didnt't torque it properly, stripped it). I used different style filter this time. So, I got it to work, leaking wise, but engine is working differently.
Maybe hose is bigger, maybe there is no enough pressure, who knows.

One more information, engine works in high idle, around 1100 rpm, when you want to get it going, you need to build rpms and then release clutch, else it'll turn off.

Have you accidentally swapped the two pipes that connect to fuel pump?
Pleased try and explain your head being full of fuel from above.
Do you mean petrol spilled onto the head of your body
Or do you mean car cylinder head inlet full of petrol?

Nope, I couldnt't swap them, cause one was connected all the time. Sadly, in this case, it was my head.

I used different stype filter, maybe that's the cause?
Can I measure fuel pressure with compression gauge.

If fuel pressure is fine, can we rule out, fuel supply as the cause?

Post picture of fuel filter you are using.

Good that you didn't mix up pipes.

Dirt could have got in pipe from filter and be making an injector stick open .
If you have black smoke from exhaust its either too much fuel or not enough air. Is air inlet blocked?

Don't mark my words, but I think it's white smoke, not black. Similar to this one.

If the pipe that broke on fuel pump is the return fuel pipe from engine and you have accidentally blocked it , the fuel pressure at injectors will be much much higher than it should be causing too much fuel to be injected-fuel rich condition.

Air inlet is not blocked I think, cause everything was working fine till filter change.

Line that I broke has red arrow on it, so I assume it's supply line.

That fuel filter won't be causing your problem.
work out if broken pipe on fuel pump is connected to fuel filter or connected to engine.

It's connected to the filter.

If it's too rich then fuel supply is not your problem.
Did you check fuel pressure regulator?
What was result?

It's too soon to jump to trying to measure fuel rail pressure unless you have the proper tool at hand.

I'm heading to home to check it.