I've spent several hours searching, found tons of info but nothing specific to my issue. working on a 50 f1, 302/c4. Installed an ir1 regulator to get 6v to the gauges then grounded the sender wires at each sender-all 3 gauges moved full scale. Replaced the oil sender with echlin op6091, temp sender with echlin ts6464 (correct replacement for the original) and purchased a new fuel sender. The oil pres. ga moved up about a 1/2 in. then dropped back down. The temp ga seems to be functioning ok but the needle starts from the hot side and moves towards the cold side. The fuel sender moves about a 1/2 in. Grounding the sender circuits still moves the gauges full scale. Vehicle is grounded well, battery to motor, motor to frame and to body. There must be something obvious I'm missing, I just don't see it. Any suggestions? Thanks in advance.