You need a MityVac to take readings at various points in the vacuum system. It will tell you whether it is the pump or something else, depending on where you take the readings. Without a Mity Vac, you can do some things but not a lot. Taking the main line from the vacuum pump loose and putting your finger over it will tell you if you have any vacuum but it's not precise enough to diagnose beyond that.
Don't know what you mean by 'evap'.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13