Johnson Evinrude Outboard Motors 1956-1970 1.5-40hp repair manual., Page 197Get this manual
FUEL SYSTEM Connect one end of second black wire to the fuel gauge terminal marked GRD and the other end to good groundIt is important for the fuel gauge case to have good common ground with the tank unitAboard an all-metal boat, this ground wire is not necessaryHowever, if the dashboard is insulated, or made of wood or plastic, wire MUST be run from the gauge ground terminal to one of the bolts securing the sending unit in the fuel tank, and then from there to the NEGATIVE side of the batteryFUEL GAUGE TROUBLESHOOTING In order for the fuel gauge to operate properly the sending unit and the receiving unit must be of the same type and preferably of the same makeThe following symptoms and possible corrective actions will be helpful in restoring faulty fuel gauge circuit to proper operationIf you suspect the gauge is not operating properly, the first area to check is all electrical connections from one end to the otherBe sure they are clean and tightNext, check the common ground wire between the negative side of the battery, the fuel tank, and the gauge on the dashIf all wires and connections in the circui are in good condition, remove the sending unit from the tankRun wire from the gauge mounting flange on the tank to the flange of the sending unitNow, move the float up-and-down to determine if the receiving unit operatesIf the sending unit does not appear to operate, move the float to the midway point of its travel and see if the receiving unit indicates half fullIf the pointer does not move from the EMPTY position one of four faults could be to blame: 1- The dash receiving un:is not properly grounded2- No voltage at the dash receiving unit3- Negative meter connections are on posi tive grounded system4- Positive meter connections are on negative grounded systemIf the pointer fails to move from the FULL position, the problem could be one of three faul ts1- The tank sending unit is not properly grounded2- Improper connection between the tank sending unit and the receiving unit on