No starting on its own Possible pump fault?

[HDIkyle]

Had a mess last night and found that when priming it builds up pressure then makes a hissing sound so there is def a leak. Sounds to be from the back right of the pump but there is no obvious leaks to pinpoint it. Also when started it empties the fuel filter before taking acre seconds to fill back up so its not getting a good enough vacuum to pull the fuel tho. Is there anything I can do.to find the leak? I was thinking of a electric pump on the fuel in to keep a lot of pressure on it?