Fuel Sending unit

[LostSailor]

So my unit went bad probably from sitting for 3 years. So I replaced it with a "universal" unit of the same size (length/depth). When I plugged it all in, it reads a FULL tank, no matter what. So I pulled it out to make sure it wasn't hitting the side of the tank (wasn't). I think hooked up my volt meter to it and manually pushed the bar from full to empty. I got a reading of 30 ohms at Full and 260 ohms at full. When i did this I noticed the fuel gauge needle barely moved, less than 1/4 tank from "full" to "empty"

So I am thinkign the resistance of the gauge and sending unit are not the same. Should I just add resistors inline to match it up??

It is a teleflex gauge, are they a standard ohm resistance??

Thanks!

[bottom scratcher]

The resistance you're getting is correct. If you're reading full when you put in in the tank, you may be hitting a baffle if it's a metal tank. If you're holding it in your hand and trying to get a reading on the guage, make sure that you have the sending unit properly grounded. The guage operates by supplying 12 volts to the tank unit and the resistor varies the voltage through ground, changing the reading. The unit you have is right for a Teleflex guage. Teleflex suggests 33 to 240 ohms.

[LostSailor]

The resistance you're getting is correct. If you're reading full when you put in in the tank, you may be hitting a baffle if it's a metal tank. If you're holding it in your hand and trying to get a reading on the guage, make sure that you have the sending unit properly grounded. The guage operates by supplying 12 volts to the tank unit and the resistor varies the voltage through ground, changing the reading. The unit you have is right for a Teleflex guage. Teleflex suggests 33 to 240 ohms.

That is the problem, it is NOT hitting anything.

SO when the unit is out of the tank I am able to move the bar up and down and that is how I get the ohm readings, yet the gauge in the dash moves very little. I know the sending unit works, as it reads 30-260 ohms. Is the gauge going out??

[bottom scratcher]

It could very well be going. Check out the Teleflex trouble shooting page for guages. It seems they list two different resistances for their guages. It looks as though that VDO guages require a 10 to 180 ohm sender. You'll have to run the test and decide. Good luck.

http://www.downloadingfiles.co.uk/teleflexfiles/library/instructionmanuals/67369.pdf