Bad fuel sending unit?

[B1B Keven]

I bought a unit from Roberts about six months ago. Seemed to work fine. The last few weeks its become more and more erratic. Now the gauge just shows full all the time (with the key on). Removed the unit reconnected the wire, grounded it and moved the arm, still shows full.

Bad?

[MBF]

To check out the function of the sending unit you can hook it up to an analog ohm meter as you move the float. If the unit is working properly you should see a smooth sweep of the needle on the meter throughout the travel range of the float. If you get a smooth sweep, check for a grounded wire between the sending unit and guage. Mike

Edited January 26, 2012 by MBFowler

[B1B Keven]

To check out the function of the sending unit you can hook it up to an analog ohm meter as you move the float. If the unit is working properly you should see a smooth sweep of the needle on the meter throughout the travel range of the float. If you get a smooth sweep, check for a grounded wire between the sending unit and guage. Mike

See, that's what's throwing me. My multimeter shows movement through the sweep of the arm. It's nearly 1 ohm at full and about 300 ohms at empty.

I just replaced the wiring yesterday.

All three of my fuel gauges act the same.

[Plymouthy Adams]

remove the unit and not connect it at all..does it still read full...? constant full would give me an idication of a short..by diconnecting the unit entirely and you get a reading will verify that

[Dave72dt]

To follow up on Tim's suggestion, you may want to check your tank ground and/or cab ground. Disconnect your gauge at the gauge and check for needle moement there also.

[B1B Keven]

Found it. The gauge wasn't making a good ground through the cluster to the body.

Thanks for the help guys!