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Gas guage

my54

my54

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Dripping Springs, Texas
Well what started out as just simply installing seat belts has turned into basically stripping the cab of all life and cleaning everything up and priming and painting the floor. (little rust) The gas gauge has not worked since I bought it, the sending unit on the tank looks fairly new but the gauge just stays buried on empty (yes I put gas in it:): Where do I start to find the problem, how can I check to make sure the sending unit is good, what should have power, how do I check the power to the gauge, ignition switch on or off is there still power being provided to the gas gauge? Any advice would be great I am pretty good at the mechanical stuff but the electrical on an auto can sometimes throw me.:confused::confused:
Mike
 
Mike,

take the sender unit out of the gas tank screw down all cables and take a ohmmeter (most of multi instrument has this option, take 100ohms). hold a cable from the instrument in the screw hole from the ring (ground contact) and hold the other cable on the contact. Now move up/down the cork and if the sender unit OK the instrument moves left/right.

this work's very easy.: volts goes follow ways: plus battery -->contact plus gauge-->through gauge to minus gauge -->sender unit plus --> through the resistor from the unit --> minus (ground on tank or similar)

Volker
 
Last edited:
Power comes from the switch to the left pole on the guage. Goes from right pole to sender, sender to ground. Most of the problems are from ground issues or broken wires. Run another ground from sender to cab. Check continuity from guage to sender to look for break. Make shure you have power to the guage. If all are right, pull out the sender and move the float up and down and see if anything changes. Use your meter to check if the ohm level changes as you move it up and down.
 
Try some logical troubleshooting first.

1. Remove the wire from the sending unit on the tank.
2. Turn on the key.

3. If the gauge goes to full the problem is either
a. in the sending unit inside the tank
b. the wire you just removed from the sending unit was touching ground.
Examine the wire carefully for worn spots that may have been touching ground. If you find evidence of worn through insulation replace the wire.
If the wire looks OK it is time to remove the sending unit from the tank. The sending unit could have electrically failed by shorting to ground, the float could have sunk, or there could be mechanical failure preventing the float arm from moving properly.

If the gauge stayed at empty at step 3 above:
4. Turn off the key
5. Remove the wire from the right pole on the gauge.
6. Turn on the key.

7. If the gauge goes to full the problem is that the wire between the gauge and the tank is shorted to ground. Replace the wire and all should be well.

Further troubleshooting requires a volt meter to determine that there is voltage available to the left pole of the gauge.

Let us know how your troubleshooting is going so far.
 
Thanks Bill. I think I can do this. My 57 has stumped me for years. Its eazy to spend money on stuff that aint broke and dont need replaceing when you dont know the basics. This really helps a lot.
 
Mine quit working a few months ago- turned out the float had a crack in it and was full of gas, so it always read empty. My float wasn't floatin. A new float fixed it right up-
 
Gas Gauge

Pulled the sending unit out of the tank and it seems to check ok with the OHM meter, have power to the gauge from the switch so now I am going to put another ground wire on and check that and run another wire from the guage to the tank and check that out, the question I have is when the truck was converted to 12 volt should some type of resistor been install in the power line to the guage or will the guage work on 6V or 12V?
Thanks
 
Gas Gauge

Well after using all the advice and techniques given to me on this site I still have a gas gauge needle that is buried past empty. I have come to the conclusion and the right one I hope that the gas gauge was damaged when the truck was converted from 6V to 12V (prior to me owning the truck) I think I am going to order a 12V replacement gauge and install it and see what happens. Can the gauge cluster be unbolted from the dash and brought out far enough to change the gauge or do all the connections have to be removed first? Does it seem reasonable that after all the testing the problem has to be the gauge?
Mike
 
Are you sure you have the right ohm gauge? Had the same problem, and also the grounding was dirty. There are machines that will dial in the voltage for those gauges. Had to have mine done that way. Good Luck
 
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