gas guage?

bronco stu · Nov 8, 2005

i've had my a 90 eddie bauer bronco for about 8 months and when i got it the gas gauge didnt work, it was just sitting on empty. so i went to the local junk yard and got a couple gauges and i replaced the old one, now it just goes to full every time i turn the power on and it stays there no matter the fuel level. any ideas of what i can try next would be appriciated

thanks stuart

BLADE262US · Nov 8, 2005

If it goes all the way to full then the sending unit wire is grounded completely . The sending unit is a wire wound variable resistor as the float goes up and down the resistance changes . If you were to take the wire off the sending unit and ground it to the frame the guage would go to full just as your water temp and oil pressure will go to hot or high if grounded . So if your guage goes to full all the way I would say that either the float hung up when you put it in or the sender was just bad from the start .

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Seabronc · Nov 8, 2005

Like BLADE262US indicated, an easy way to test to see if the problem is the sender or gauge is to remove the connector at the tank and put the key in RUN. Then use a meter to see if you have approximately 5 volts between the contacts, if not change the instrument votage regulator. With it removed, the gauge should read where it does with the key in the OFF position. Then take a wire and short between the two contacts and the gauge should read full. If you can get a 22 ohm resistor, place it between the connector contacts and the gauge should read 1/2 scale and a 73 ohm resistor should put the needle on E. You can get resistors at Radio Shack for this test.

To test the gague itself, use a ohm meter with the gauge disconnected , you should get between 10 and 14 ohms. If not the gague is bad.

Good luck,

>-

firelt90bronco · Nov 17, 2005

i'm a mechanic and i have the same problem, only mine stayed on half a tank. I recently changed my valve cover gaskets and when went to turn it over it didn't start. At first I thought it was a bad distributor and then I thought it was a fuel filter then a pump. Finally I realized it had no gas, After that I replaced the sending unit. In my profession, I would just replace it, while your down there, just replace it. Good Luck and keep an eye on your odometer until you replace the sending unit.

>-

Seabronc · Nov 17, 2005

Like BLADE262US indicated, an easy way to test to see if the problem is the sender or gauge is to remove the connector at the tank and put the key in RUN. Then use a meter to see if you have approximately 5 volts between the contacts, if not change the instrument votage regulator. With it removed, the gauge should read where it does with the key in the OFF position. Then take a wire and short between the two contacts and the gauge should read full. If you can get a 22 ohm resistor, place it between the connector contacts and the gauge should read 1/2 scale and a 73 ohm resistor should put the needle on E. You can get resistors at Radio Shack for this test.
To test the gague itself, use a ohm meter with the gauge disconnected , you should get between 10 and 14 ohms. If not the gague is bad.

Good luck,

>-

29217[/snapback]

In reading what I said, I noticed that I left something out. When checking the voltage at the connector, a lack of 5 volt could also be a wiring problem .

>-

k1w1t1m · Nov 22, 2005

BTW when the connectors on the DS fender are disconnected I noticed my fuel guage pegged full. I never found out why, I just noticed it.

HTH

Tim

gas guage?

bronco stu

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firelt90bronco

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