1984 Toyota diesel

Lately my toyota has been harder and harder to start I was able to use the primer on the fuel filter to get it started but lately when using it it feels as if its not working and just pushing air at some point it seems to build suction when it does this I am able to start I disconnected the fuel line form the filter with the key in the ignitionand turned on but no fuel comes out I am unsure if there is anything else needed to allow pump to work also will any fuel pump work or does it have to be a diesel pump I believe this is a intank pump is there anything else to check for as far as fuel not pumping? Thank you for any assistance anyone can offer