byoung36 18 #1 Posted July 21, 2019 (edited) I found a donor 520 that was suppose to have a good running engine when it was parked several years ago. I have been trying to start it to hear it run before I pull it, but it doesn’t have any spark. The spark plug with spark when I turn key on but nothing when turning over. Any help will be appreciated, these two are my first experience with Onan. Also the donor Onan has 800 hrs and 110psi compression on each cylinder. Does anyone know what the spec.compression should be? Edited July 21, 2019 by byoung36 Share this post Link to post Share on other sites
lynnmor 6,707 #2 Posted July 21, 2019 110 is good. If you get one spark with one turn of the key, check connections on top of the coil, if that is OK, suspect ignition module behind flywheel. The Onan engine manual gives instructions for testing ignition components. Share this post Link to post Share on other sites