Will wrote:The fuel gauge is flashing one bar.
My inference is that a display of one flashing bar is abnormal. Consult the owner's manual of the Yamaha fuel gauge to determine what the indication of one flashing bar means, and provide that information in a follow up. It is not clear to me if the essential deviation from normal is the flashing condition or the one-bar condition. Provide further information about this.
Will wrote:I disconnected the sending unit wires yesterday and I am still getting one flashing bar.
Your test does not provide any basis to draw a conclusion about the location of the fault.
More information neededWhat is the actual tank level as determined by some other basis than the Yamaha tank level gauge? This information is necessary in order to have a basis to infer a proper resistance reading in the sender.
Suggested Test ProcedureI suggest you temporarily disconnect the circuit between the gauge and the sending unit at the tank end of the wiring. Then measure the resistance of the sending unit right at the fuel tank.
The expected resistance of a tank level sending unit made for use in the USA is likely to be between 33-Ohm (at full tank) and 240-Ohm (at empty tank). (A separate article has more information about
tank level sender resistance.) Based on an inference about the actual tank level, compare the resistance reading to the inferred actual tank level to see if they are congruent.
If the tank level sender resistance is not in the proper range, then the fault is likely in the tank level sender.
If the tank level sender resistance is in the proper range, then reconnect the circuit from the gauge to the sender. Move to the gauge. Temporarily disconnect the circuit from the gauge. Measure the resistance in the circuit. It should be the same as you measured at the tank sender directly.
If the resistance of the circuit at the gauge end of the wiring is different than at the tank end, the problem is in the wiring between the tank and the gauge.
If the resistance of the circuit at the gauge end of the wiring is the same as at the tank end, then the fault is likely in the gauge.
Perform the above procedure and reply with your observations and readings of resistance.
In my estimate, the component with the highest probability of failure is the wiring between sender and gauge, including loss of one leg of the circuit. Often the negative return (or ground) side of the circuit may be missing. Or there may be corrosion in a connection.
Regarding connections, do not trust an electrical connection in low-voltage circuits (like a 12-Volt DC circuit) based only on the appearance of the connection. It is common for connections to have the appearance of mechanical integrity, but for there to be an electrical discontinuity in the connection. This is due to the formation of a very thin layer of insulating material (corrosion) in the connection. At low voltages, electrical current flow can be stopped by a very thin layer of insulating material which may not be readily seen. Sometimes a disassembly of the connection, then cleaning of the terminals with WD40 and possibly some very soft abrasion (with perhaps 600-grit cloth and wet sanding with WD40) will be necessary to restore an electrical connection.