Trying to get the fuel gauge to work on my 68 rr sweep dash. I have a new tank and sender. I have the dark blue sender wire hooked up and the wire is good from front to back. I checked to see that the (regulator?) is pluged into the back of the cluster, and it is present. I also added an existing ground wire from the gauge cluster housing to a ground.

Any other things i should check? When i ground the sender wire the gauge does not go to full.

At this point it is time to try a different gauge..
You should also check out the round plug in pin connector on the back of the dash and pins to be sure none of them are damaged or not making good contact.

If the instrument VR is working you should see voltage at the gauge. With a stock VR it may be pulsing 12 volts, or with a solid state regulator, about 5 volts constant. Either way, with the sending unit wire grounded it should read Full or above. If it does not read at least FULL the problem could be the gauge or the instrument VR output. Easiest thing would be to swap out either item with a known good one. If the Voltage regulator is good, you may be able to re-calibrate the Fuel gauge by slightly moving/rotating the small teeth behind the small holes on the back of the gauge?
If the gauge responds when the sending unit wire is shorted to ground, but not when connected to the sending unit, make sure the sending unit is grounded. The factory used a small strap that cliped to the fuel line comming out of the tank jumpering to the cars chassis mounted fuel line.

It is my understanding that many vendors still sell "sending units" (designed for GM cars) for MOPARS use & the ohms output is all wrong for OEM Mopar gauges.

Do a search on here, others have had this problem & found proper source. I have this problem also, at a full tank my gauge only reads a little over half full.

Edit: MOPARTS member "Mopar Grandpa" reported senders from Inline Tube worked with zero problems; http://www.inlinetube.com/



John

My sender is from inline tube. When i ground the sender wire the gauge still doesnt go to full/move. Now, when i look at the back of the cluster...there is two studs for the amp gauge and then behind the fuel gauge there looks to be sutds with speed nuts. Does any sort or wires hook to these/the backside of the gauge? I know on my challenger there was some sort of light blue jumper harness i had to plug in for the fuel gauge to work.

the nuts are for tha amp guage- ignore them-but make sure they are tight!!!!!!!!!

as stated- check the pin that is on the board that feeds the fuel gauge- better still- solder all of them as they are a source of issuses later!!!


since you had grounded the wire at the tank and there is no full reading......

do the same by grounding out the temp. sender and see if it pegs out- if so the VR is probely working right! if not....

check the voltage of the VR- it will be pulsing to 12 volts- but if you average it out it's about 5 volts to feed the gauges!!! if it is old- replace it!!

best bet here as stated it to find another fuel gauge and swap it out.