The fuel gauge usually burns up if it does not have a resistor (not always some say). If your tank has never been cleaned you may find it is the float gauge itself that is the problem (crud & corrosion). Speedo could be internal mechanism or the cable no electrical connection there. Also the oil pressure is a tube from a lower block fitting to the gauge, no electrical. It is a small 1/8" tube they can plug up or get pinched. Usually the amp gauge if hooked up correctly functions fine on either voltage. Temperature gauge will come from the rear of the head with a copper or steel tube to the gauge. Look for breaks in the line (sealed unit) if the ether has leaked out you will need to replace it, no electrical connection. This is a continuing topic here so search for specifics others will chime in as well.
