1989 300e fuel pump question

[300ESUPER]

How do I check if my fuel pumps are working properly. I have a starting problem where I have to rev the car to start it. The car also shakes after start up for a minute or two.

The fuel pumps in my car are about 2 - 3 years old each. I had this problem before and the mechanic told me this that the fuel pumps were the problem. When I changed the pumps the problem went away and now it is back. The fuel filter is only 2 weeks old.

Help please,

Fab