Fuel gauge quit, sending unit.

[VulcanOne]

I have a 55 gallon tank and like everyone else with one my gauge always registered 3/4 when it was full.  Well, not it just quit working all together.  The needle doesn't move at all any more, just stays below empty.  Any advice?  Think the sender just quit or is stuck?  Anything I should check for before dropping the tank?  Are there after market sending units for these and if so where would I go to get one?  

Well, I grounded the wire from the sending unit and the gauge went to full.  So it must be the sending unit or the ground.  I'll drop the tank and check it out.

I bought a universal replacement sending unit from a local auto parts store made by Sun Pro.  I hooked up the wires to it before installing and it works except when I move the arm to the full stop the gauge only goes up to 1/4 tank.  Now I am kind of stumped at what to do.  Any suggestions?

Well, today I order a aftermarket fuel level sending unit from J.C. Whitney.  The web page is below.  Hopefully I will be able to adapt to the pick in my tank.  I also found a unit out of a 79 Dodge Ram 350 van that I ordered.  The guy put an ohm meter on it and says it went from about 9 to 80 ohms.  Hopefully between the two of these I will find something that will works.

http://www.jcwhitney.com/autoparts/ItemBrowse/c-10614/s-10101/p-100000162409/mediaCode-ZX/appId-100000162409/Pr-p_CATENTRY_ID:100000162409


Thanks

[Rodney]

Hello Vulcanone and Welcome to ACOC.
The first thing I would check is the fuse for the gauges.
then the ground wire to the gauge which I think is on the top of the tank going to one of the screws that fasten the sending unit to the tank. It's been several years since I had my tank out so if anyone else knows different please let us know. you may be able to do a quick test to see that the gauge and wire going to the gauge is ok by finding the wire which goes to the sending unit and ground it to the frame and see if the gauge moves. If it does your problem is in the sending unit or ground to the unit. I read some where that the gauges are what came in the OEM tanks just put in the larger ones. this is why they don't read full when the tank is full as it isn't really the correct unit for the tank.
let us know how it goes

[Andy Illes]

Vulcan... Conrad posted in Tips & Tricks about the voltage regulator on the instrument cluster.  If your other guages read funky too, try that fix.  If it's only your gas guage, most aftermarket senders I've seen allow you to change the length of the sender float-arm.... sortta like the ball in a toilet tank.  Since you got a full reading by grounding the sender-to-guage wire, the guage circuit is ok.  Did you try to get a full reading raising the float alla way up manually?  If you tried that and it still didn't read full, then there's a mismatch in the resistance between the sender and guage.  

Conrad's link sez to check the sender with an ohm meter.... the value at "full tank" should be 8.6 to 10.6 ohms, and 61 to 85 ohms "empty" for correct readings on the guage.  If the resistance at full is higher... you'll get a low guage reading.   If it's within spec, either the instrument voltage regulator jobbie (see Conrad's link) is outta whack, or the guage is bad.

Good luck... and like Rodney sez.... WELCOME!!!!!