So what is exactly Black Death? I recently read about it me now slightly worried.

I recently replaced the o-rings and crush washers for the deliver valves since I was leaking fuel and could see the drip and smell the fumes in cabin.

Now there is no more fuel leak but I can still smell the fuel. I do remember when taking of the cover I could see fuel in the head. The smell is very strong towards the back near the cabin.

Is there anything I should look out for or other symptoms I should be aware of? And maybe some advice in fixing the fumes which gets very strong at times.

I'm driving a 95 e300 om606