Tach. and fuel gauge help

[sea nymph18]

I have just bought a used 1995 alumaweld johnson 112 spl.... the tach. sits at 8 but if wiggle the wire (that goes to the arm) it will go to 6. Fuel gauge just sits at empty. replaced the sending unit. If i hook the pink sending unit wire to a negative side of a battery and the ground to a positive the gauge will show full... any troubleshooting ideas or anything???

 

[95yj]

Re: Tach. and fuel gauge help

The fuel gauge is easy to figure out where the problem is. You said if you ground the sending side of the gauge and apply +12vdc to the positive side of the gauge, it reads full so the gauge is not the problem.

The sending unit has two wires. Input side is connected to ground. Make sure that you have a good ground there. Short across the two wires (apply ground to the sending side of the sending unit) Does fuel gauge read full. If not, then the wiring between the tank and the gauge is bad. If it does, then your new sending unit is bad also.

Check the sending unit with an ohm meter. With float arm in full position, should read 30 ohms. In empty position it should read 240 ohms. ( +- 5 ohms on both)

Tachs problems are almost always the tach. Check that your wire from the gauge to the coil or ignition is good and your ground to the gauge is good. If the wiring is good, it is most probably the Tach