i changed my pickup/sending unit a little while ago. was hoping my gas gauge would start working because the sending unit i took out was crusty. but its a no go. it will read half a tank when i know there is only about a gallon in there. the arm was adjusted properly to read an empty tank so i know its not that. while cruising if giving it gas the fuel gauge will start to climb. ive done the search on here but came up empty handed. i recall reading something about it on here years ago but cant find it now. any help would be appreciated.

1. Make sure there is a ground wire from the sender in the tank to the chassis.

2. Does the temp guage work right? It runs off of the same 5 volt voltage limiter in the dash; If the temp guage is good, then the limiter is good. If the temp guage reads badly, then it is necessary to start with the voltage limiter.

i will double check and probably add a ground just for good measure. the temp gauge hasnt been hooked up for a long time. went aftermarket.

Yes a good ground between sending unit spout and metal fuel line. Just because you have a good electrical connection to fuel line doesn't make a good ground. Fuel line is held in place by a hand full of clips that snap into various holes along frame which all are coated with fifty years of grime, rust, paint, and undercoating making for a crappy electrical path to ground.

Also the dash gage cluster has to have a good ground path for the voltage limiter and its other electrical devices as to operate intended. This path is via the screws attaching cluster to metal dash. One can improve both sending unit and gage cluster ground by making up and install secondary grounding conductors to augment factory method.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

so if i wanted to add a ground to the gauge cluster, where would be a good place to ground the cluster? i can tie into the dash for a ground just not sure where to go from the cluster.

I'm not up on what your gage cluster looks like, but generally speaking you have to tie the metal frame of cluster to metal frame of dash or sheet metal bracing of dash or body sheet metal some where out of sight under dash electrically with a 12 gage wire. 12 gage will easily carry cluster's total amp load.

You may have to solder that new ground jumper, or just secure it with a screw to cluster; dealer's choice. Where ever you attach said jumper to ground point should be to something that has zero voltage drop between that point and negative battery terminal. This implies that one has cleaned and remade all ground connections from battery negative terminal to wherever they terminate such as block, and head to fire wall. Zero drop on ground side of any circuit is most important to correct voltages in all of car's circuits, and particularly critical in ignition & charging circuits.

You can test for voltage drop between battery negative terminal by attaching a long jumper wire to VOM test lead so as to easily reach under dash.

I know this seams to be getting complicated and picky, but little details in electrical work can make a big difference in reliability.

One other test you can perform is to check the new sending unit's resistances. At tank, connect one lead to body of sending unit, and the other to unit's electrical terminal. Chrysler's stock spec: empty it should be 73 ohms (+ or - 12 ohms), and full it should be 9.6 ohms (+ or- 1 ohm). If this is not the case it could be because of aftermarket sending unit is built to off spec resistances from factory unit, and or float arm is not traveling same ark as factory unit and need further adjustment.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

For the sender ground, the factory foten used a strap between the sender spout and the main line. and used the fuel pump conneciotn to the block. You can do that or put a ground direct from the sender to the chassis; I would prefer the latter.

If you have a voltmeter, then take the wire off of the sender and check the voltage coming out. It should cycle between 0 and 12 v on and off in a regular cycle. (This is sometimes hard to tell with a digital meter.) If it does this, then that is a first check on the voltage limiter.

Another test you can do is to ground the wire to the sender for a few seconds and see if the guage quickly moves to full. (Do not ground for long as this could burn out the guage.) It is better to use a 10 ohm resistor and tie the wire to ground through that resistor and see if the guage reads full; you can leave that on for a while.