The Ranger Station, The Ranger terminal Staff, no one the original poster space responsible because that you act this change to your vehicle. By doing this modification and following this how-to you, the installer, take full responsibility if anything is damaged or messed up. If you have questions, feel totally free to pm the original poster or questioning in the ideal section of The Ranger terminal forums.

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This is an explanation on exactly how to trouble shoot friend fuel level sending unit and what the ohms you require (depending ~ above the year of girlfriend truck) because that a new aftermarket fuel level gauge or to use a your manufacturing facility gauge v a brand-new fuel cabinet that has an after sector sending unit. Note: the reason is if you perform not have actually the correct ohm selection your gauge will certainly not work.

Tools Needed:

An electricians meter (that reads ohms)Flat head screw driver

Parts needed:

(All parts in perform are based upon if components are poor or need repair.)

Possibly brand-new sending unitAuto wireButt connectors

IMPORTANT – things you need to know prior to you start:

The fuel gauge is a reasonably simple electronic. The fuel gage circuit consists of the sending out unit in the fuel tank, the gauge in the dash, and also the wiring and also dash wiring (or circuit board) between them. It’s power resource comes native a voltage regulator that is 5 volts. 


Here is a picture of a sending out unit on a 1988 Bronco II wiring diagram:


How it works:

The sending unit is a change resistor. That resists the circulation of present from the ground to the gauge, depending on the place of the float within the tank. As soon as the float arm is in ~ the full position, it decreases the resistance in between the gauge and the soil (basically there is shorter distance because that the existing to flow). The an ext current the flows v the meter, the greater the gauge needle moves.

The gauge uses a 5 volt pulse supplied by the instrument cluster’s voltage regulator.


Problem; The gauge does not job-related (the needle does no move).

Turn the an essential to the on position for this operation. If you can gain to your sending unit wiring harness without dropping your tank(s), go ahead and also pull it. If not, then drop the tank(s) and also pull the harness. Gain a item of wire (jumper wire) to attach to the optimistic of the harness, and also the an adverse of the sender housing. This have to make the gauge jump to full.

If the gauge’s needle moves:

It method that the wiring is fine and it is your most likely your sending unit. You’ll need to remove the sending out unit from the tank for inspection and testing.

Here is a snapshot of a 1985-1988 sending unit.


(The black color bar at the bottom is the float)

When you remove the sending out unit, check the float, rise arm, wires, and the sender itself to for sure it’s intact and also functioning properly. Over there is a possibility that the arm is binding, so move it up and also down come make certain it moves freely. 

Reconnect the gauge wiring come the unit and also ground the unit. Move the float eight up and also down. If the gauge reads complete in the complete up position and also empty in the complete down position, then the sending unit is good. Verify by hooking increase an ohmmeter to it and making certain it reads:

8-12 ohms full and 70-73 ohms north (pre-1989)16 ohms full and 158 ohms full (1989+)

If not, the sending unit requirements repaired or replaced.

I have actually an 1988 Ford Ranger and my sending unit was no working. The gauge worked, so ns knew there had actually to be something wrong v the sender. Currently if you have a mechanically fuel pump prefer mine, then you can’t acquire the sending out unit for that year, since they quit making it. It’s stupid since it’s simply one metal tube on the sender plate, and also a 2 prong connection. I had to gain a sending out unit for a 2.3L Ranger and modify it. It works great.

If the gauge does not jump to full:

Ground the sending unit wiring come a great chassis floor (instead that the sending unit housing) and also watch the gauge. Walk it currently jump come the ‘Full’ side? The strength supply come the gauge has actually been interrupted, (check fuses), the gauge is defective, or the cable from the gauge to the sending unit is open or has a rest in it.

To check the voltage regulator for proper duty use a tester. Probe the connector through the tester, it have to flash on and also off.

I hope this to be helpful. I want to thank for the details I check out about.

See original Post:

Other connected Problems:

Float no Floating:

Remove the pump native the tank and also see if the rise is quiet floating. If the isn’t floating, an interpretation it has actually sunk, then it’s due because that replacement.

Sending Unit Contacts:

The contact on the sending out unit itself can likewise wear out, but that is less common.

Question: What causes the gauge to read means past complete for 3/4 tank and also then fly under to reading empty in roughly 20 miles?

Answer: contact on the sending unit space worn out, and do not send a analysis to the gauge once it it s okay to a specific level.


See all those gold horizontal lines? each one sends a various level of resistance come the gauge. As the contact point moves throughout them, they wear the end over time, notice how they room all worn down? That’s probably what her looks prefer from 3/4 method down.


Aftermarket Gauges:

Note: If you are installing an aftermarket fuel gauge you have to make sure that the gauge is the same ohms together your sender. It will certainly not work if they space not the same. The same goes for after market sending systems that you might get with a fuel cell. Check your accuse or speak to manufacturer because that information.

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Manufacturer that Gauges:

Auto Meter (have fuel gauges for ford)Equus (have fuel gauges because that Ford)Sunprothere are many others.