Testing gas tank sending unit

[chronos]

86 16g drivers side tank. Can I check the sending unit
by plugging in the wire into it while it is out of the tank
and turning on power?
How can i tell if its working?
Thanks for the help

[choptop]

PLEASE DO NOT PUT POWER TO IT!!!!! It is a variable resistor that goes to ground. You can connect an ohm meter to it and check for resistance, but depending on where the level is at will determine resistance, and unless you can move the float up and down then you can't really tell if the resistance is change. Connect one lead to the wire, and the other end to the tank or ground and see if the is any resistance. Once again, this will not necassarily tell you anything, unless it shwos an open circuit. You can, however, groun d out the wire, and the fuel gauge should show full. ( I think that is right) But if you put power to it, it will ground out and possibly cause a fire.

[Fordeatinz71]

well, if you have it out of the tank then just use a multimeter and check for resistance, and see if it changes as you move the float...also, make sure you check for holes in your float.  if you get one, the float will fill with gas and will sink to the bottom, giving you a reading of empty all the time...

[choptop]

Good eye there fordeatinz71, I saw turnig power on and missed the out of tank part". Yes if you move the float up and down slowly, the ohm reading should change smoothly. But if you are this far, is it just as easy to replace it. I have not priced one, so I don't know how expensive they are.

[chronos]

Thanks guys...got it checked andits working