Going to try repair my fuel tank sending unit we will see how it goes

[WileE]

The REAL problem here is you think you KNOW IT ALL but your reading and/or comprehension skills are lacking!!!!!!!!!! PSS the BOLD TYPE WAS AN ACCIDENT but it wasn't this time!!

No need to get your panties all wadded up over it. You obviously think you know it all anyway...so nobody else need reply.

 

[kiwigtx]

I think God has gifted us with a replacement for the late Bob Renton.

 

[Geoff 2]

Oh no.......................

 

[oldchevelle541]

There is a company out there that restores the original units. It costs a bit but saves a lot of aggrevation.

 

[BLK 68 R/T]

I think God has gifted us with a replacement for the late Bob Renton.

Just your opinion, of course…

 

[Floyd]

I stumbled onto this guy a couple months ago. Great service at a very reasonable price:

Andy Russell, phone: 330-260-1724. He restored two OE fuel senders for me. Cost was $75 shipped for each. I have installed both and they work as they should. He told me he also has many parts on-hand so maybe he can help with parts alone.

He has a website but it doesn't seem to be working. Might be on Facebook as well.

https://www.russellrebuilds.com/

 

[Vaanth]

Fuel Sending Unit Checking Considerations

When testing or adjusting the fuel sending units on most rear wheel drive Chrysler products from 1960 to 1993, consider the points in the following sections.

Physical Considerations​

The routing and angle of the pickup tube affects the fuel entry point and the relative range of the float arm. This does not affect the electrical (resistance) values of the sending unit, but affects the relation between the values and physical fuel. Ensure the pickup entry point is near the bottom of the tank.

The position of the float arm pivot and the angle of the float arm does not change the resistance values of the sending unit, but can vary the correspondence of these values where the low (empty or high resistance) and high (full or low resistance) points of contact on the variable resistance occur. The float arm pivot follows the position of the pickup tube, but the arm can be bent to change the float arm angle.

The physical ground connection from the external part of the sending unit to chassis ground must be solid to afford a proper electrical connection. This was accomplished with a clip-on connector between the fuel exit tube and the metal fuel line on the vehicle until the late 1970s, when a dedicated ground lead was added to the sending unit in various applications. The grounding to the chassis subsequently occurred between the fuel line and the chassis by contact through the fuel line clips. All of these points must be sound for good connectivity.

Electrical Considerations​

The fuel sending unit contains a variable resistance and several contact or connection points. Any of these can be a bad contact or high resistance point.

The variable resistance consists of a non-linear wire wound resistor and a wiper connected to the float arm. The wire winding of the resistor is insulated from the housing. One end of the wire winding is physically fastened by an insulated brad to the housing so it is not electrically connected to it. The other end of the wire winding is crimped by an insulated brad to a ribbon or wire conductor leading to the external connector of the sending unit. The wiper contacts the variable resistance and connects it to ground through its contact at the pivot point. A spring loads the pivot of the arm and also adds ground connectivity. The following image shows an example of the variable resistance assembly. This type is mounted at the external mount flange. Others have the resistance housing mounted down on the fuel tube.

Potential high resistance points can occur at any of the following areas of the variable resistance portion:

• Pivot point contact to the housing.
• Crimp point of the resistance winding to the connection leading to the external connector.
• Crimp point of the wire or ribbon conductor leading to the external connector.
• Wiper to the resistance winding- this can be due to contamination, oxidation or wear of the wiper point, or loss of tension of the wiper.
• Surface high resistance of the wire winding due to varnish or other contaminant. This can usually be cleared by cleaning or exercising the wipe over the winding.

The following images show a disassembled variable resistance, wiper,and the wiper contact:

The external mounting flange of the sending unit electrically consists of a post type connector and the fuel tube which is the ground path to the variable resistance housing and float arm/wiper pivot. Potential high resistance points can occur at any of the following areas:

• Crimp point of the wire or ribbon conductor at the external post.
• Loss of electrical connectivity of the fuel tube at some point to the variable resistance housing and float arm/wiper pivot.
• The vehicle wiring connection to the external post.
• The connection of the sending unit ground to the vehicle chassis ground, via the tube to tube connector and/or ground wire.

The following images show the inside and outside views of the mounting flange and connections:

Resistance Values​

Total end to end resistance of the wire wound resistor is about 81 ohms.

Resistance values of the variable resistor as measured from the external post connected end of the wire wound resistor through the wiper to ground at "empty", "half", and "full", is as follows:

Chrysler Specification:

• Empty = 72 Ω
• Half = 22 Ω
• Full = 9 Ω

Miller Special Tool C-3826 Specification (used by Chrysler for field testing):

• Empty = 75 Ω +/-5% -> 71.2 - 78.8 Ω
• Half = 22 Ω +/-5% -> 20.9 - 23.1 Ω
• Full = 10 Ω +/-5% -> 9.5 - 10.5 Ω

Measuring Low Resistance​

When measuring low resistances such as continuity or low resistance values of the sending unit, account for the resistance of the test leads connected to the measuring device. This can be done by shorting the leads together, noting the resistance, and subtracting it from the measurement readings, or use the meter's relative setting (if equipped) similarly with the lead shorting, or use a meter that measures conductance and convert accordingly, or use a four wire ohms measurement setup with the appropriate device.

Basic Principles of Operation​

Following is a simplified description of the fuel sending unit and gauge operation. For more information, see the Chrysler service manual(s) or Chrysler’s Master Technician Service Conference publications covering this topic.

The thermal type fuel (plus temperature and oil pressure) gauge used in the subject vehicles are Chrysler’s adaptation of the King Seeley thermal gauge concept. The gauge functions from an applied constant voltage to the connected gauge and sending unit. The constant voltage is supplied by a voltage regulator that drops the electrical system 12 volts to 5 volts. The 5 volts is applied across the series connected gauge and variable resistance sending unit.

With the resistance at a high level (ie. “empty” with the float near the bottom of the tank), current through the series connected unit is less, the thermal gauge heats less, and the needle movement is less, indicating near the “E” point on the gauge face.

With the resistance at a low level (ie. “full” with the float near the top of the tank), current through the series connected unit is more, the thermal gauge heats more, and the needle movement is more, indicating near the “F” point on the gauge face.

As the float level, and subsequent resistance value, varies between high and low, the gauge position varies accordingly.

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Content and photos: Gary Lewallen, aka Vaanth
19 November 2025

Diagrams Courtesy Chrysler Corporation