Ground the sender line, turn on the key. You should get a full reading in a VERY short time. Don't leave it on longer than to test. Can you tell if the temp gauge is working?
Temp and amp gauge work perfect. The gas gauge did until I reinstalled the new tank. And I usd the same sender that was brand new that worked before I took it out. . So the wire that goes on the sender.."snaps onto it" ...ground it for a short period. And see if the gauge climbs? If it does?