2-5/8" Classic Dual Gauge | Water Temp + Fuel Level (Celsius) | Top/Bottom

The first step to troubleshoot fuel gauge issues is verifying a good connection on signal and ground to the sender. You can either inspect the connections closely, we recommend using a multimeter to measure the ohms at the harness on the gauge side. If you have 0 ohms or open line, you don't have a good connection or the sender is bad.

Next is to ensure it is calibrated, if you have done manual calibration both empty and full conditions need to be set, or it won't read accurately. If you have done a preset calibration, ensure that it matches the ohm range of your fuel sender.
If you don't have a multimeter or don't want to measure the ohms, you can cycle through the presets to see if one works. If not, do manual calibration.
The CJ series gauges are preset to 70-10 ohms and work with stock jeep senders.

If the pointer is rapidly moving, you likely have a bad ground. It could also be electrical interference if you have the signal wire routed near high voltage components like coils, or if it is combined with a fuel pump. 
We recommend using our 2-wire fuel harness that runs a direct ground and signal to the sender.

If your gauge is staying at empty regardless of what preset you use, it likely has a bad connection and isn't getting an ohm reading. Every gauge is tested before it ships.

If the threads are wrong, you will need an adapter that changes your port to 1/8" NPT. We have some available, ensure you verify it is the right one.

If the sensor fits the threads but is too long, you can try trimming it up to but NOT past the notch. Trimming past the notch will damage the sensor. If it still does not fit, you can get a radiator hose adapter with a 1/8" NPT port.

If the gauge does not sweep on startup, it is not getting power. Verify the red, white, black power harness is connected properly.

If it sweeps but is not reading at all, ensure the signal harness is connected and pressed in firmly on both sides.

If it's still not working, test the signal harness for continuity with a multimeter. If you have both probes on the metal terminal and it reads "OL" or 0 ohms, the harness is bad.  Call or email us to get a replacement harness. You can put paperclips in the harness connector if needed to get a good contact point.

If the harness is testing good, the next step is to measure ohms coming from the sensor while it is warm. Refer to the chart below, if the ohm reading is close to 0 or it's an OL, you need a new sensor. We recommend reading the ohms at the gauge side to verify it is getting to the gauge.

Our fuel level gauges are programmable, they are compatible with any OEM or aftermarket resistance range. When setting up your gauge, follow the simple calibration setup found in the installation instructions.

Fuel Level Gauge factory default resistance settings are:
240 Ohms = Empty
33 Ohms = Full

Fuel Level Capacitance Universal Sender* (sold separately): If you are using a fuel level gauge from Speedhut with the Fuel Level Sender from Speedhut then use the gauge's factory default range (240 Ohms = Empty and 33 Ohms = Full).

*Additional electronics may be required for use with other brands' fuel level gauges (If used with a fuel level gauge from Speedhut then no additional electronics are required).

The sender and gauge must be grounded to the same source to operate correctly.

The sender's ground path is its mounting threads. Ensure that what the sender is threaded into is grounded to the same source as the gauge.

Use Teflon paste on the sender threads to secure the seal and maintain a secure ground connection. Teflon tape will NOT assist the ground connection.

Calibrate preset fuel level on dual Speedo/Fuel gauge:

Dual Speedo/Fuel manual calibration:

Manual calibration for standalone fuel level with float-style sender:

Calibrate your Quad gauge fuel level (manual or preset):

Calibrate EL-style fuel level (pre 2022 orders):

Test your float-style fuel sender:

The fuel level gauge can be manually calibrated to your existing fuel tank sender or you can select one of the preset calibration curves. Factory default setting is 240 ohms Empty and 33 ohms Full. No calibration is necessary on senders with this output.

***Selecting a calibration preset***

1. While gauge is powered up, press and hold button down for 10-12 seconds until pointer swings and stops at ‘1/8’ tank then release the button. You are now in calibration mode.

2. Press and release button to toggle between available resistive ohm options (see figure 1). Pointer will travel to each available setting with quick button press. At desired ohm range press and hold button down for 4 seconds to select that range.

3. Pointer will then travel to ‘E’ gauge will exit calibration menu and display current fuel level.

Note: On gauges with LED on front, the LED will blink 2 times to indicate the setting is saved.

*** Manual calibration***

Note: make sure fuel level sensor is hooked up to gauge and is at the appropriate empty or full state you wish to calibrate. Fuel level sensor MUST be attached to gauge during calibration procedure(s).

If your sensor is different from the preset ranges you can manually calibrate the gauge. You will need to program the 'Empty' resistance and the 'Full' resistance.

1. Follow steps 1 & 2 above and select (manual calibration ‘F’ see figure 1).

2. Release button (pointer will oscillate between ‘E’ and ‘F’.)

3. When pointer is at ‘F’ or ‘E’ - press and hold button for 4 seconds to calibrate that condition. For example: If the tank was drained with no gas you would select the Empty position ‘E’ on the dial.

4. Pointer will then travel to ‘E’ or ‘F’ depending on which end you are setting. Gauge will exit calibration menu and display current fuel level. Repeat procedure to set OTHER end point. Note: Until both empty and full points are calibrated the gauge will NOT display the fuel level accurately.

Note: On gauges with LED on front, the LED will blink 2 times to indicate the setting is saved. You can reset gauge calibration as many times as needed by repeating above steps.

The process of programming a fuel level gauge is detailed in the instructions.

Click here to download our fuel level gauge installation and operation instructions.

Making a comparison to a Temperature Gun reading should be used as a basic comparison only. A temperature gun only measures surface temperature, and does not measure internal temperature. Surface temperature will always be cooler than the coolant inside the engine. A common temperature difference would be between 5 and 25 degrees, between the water temperature gauge and a temperature gun. This depends on the efficiency of the component being shot with the temperature gun to dissipate heat. So, if your gauge reads 195 and you point & shoot and get a reading of 185, you can safely assume that you are seeing a reasonable, and realistic comparison. Only use a temperature gun to make basic temperature comparisons. Understand, that when everything is working correctly, the gauge will usually read higher since the gauge measures core temperature, and the temperature gun measures surface temperature.

Fuel Level Capacitance Universal Sender* (sold separately): If you are using a fuel level gauge from Speedhut with the Fuel Level Sender from Speedhut, use the gauge's factory default range (240 Ohms = Empty and 33 Ohms = Full).

*Additional electronics maybe required for use with other brands' fuel level gauges (If used with a fuel level gauge from Speedhut, no additional electronics are required).