Hello need help figuring out whats wrong with my 1992 honda civic dx

When i bought it, she wouldn't start up I took out the main relay cleaned up some dark residue that was on some of the contacts and it ran for a few days but now again it will not start yet again.

I've replaced the fuel pump and relay and still not starting up.

Any idea why it would run for awhile but then stop again?

Thanks for any help

 

Other possible causes may be faulty PCM, Crank Sensor and Fuel Pressure.