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1994 fuel guage


swamprat

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lexington KY
Vehicle Year
1994
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
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Manual
2WD / 4WD
4WD
I have a 1994 ranger 4.0. Bought a few years ago and for the most part sitting in garage. When bought it had a bad flex plate and I have been converting to 5sp. Conversion is done but when I start the truck the gauge goes past full. Key off it is on full then goes fast full key on. The tank has just a few gallons of gas in it. Is this a guage or sending unit problem? Read other post on checking ohms but my wire colors dont match so dont know which ones to check. Pretty sure it worked when bought the truck. This is the last thing I need fixed so I can drive it.
 


RonD

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The fuel gauge wire is disconnected somewhere, or ungrounded.

1989 and up gauge/sending units use (empty)16-158(full) Ohms

0 ohms = short circuit so gauge would show below empty
1,000,000,000 ohms = disconnected so gauge would show above full

Fuel gauge uses a 5volt Pulse power supply so it won't read on volt meter.

There should be 4 wires coming from the fuel tank
1. Fuel pump power(12v), usual wire color Pink/black stripe
2. Fuel pump ground, usual wire color Black

3. Gauge wire, usual wire color Yellow/white stripe
4. Gauge ground, usual wire color Orange

If yours don't match these colors then some one has rewired the fuel tank and that could be the problem, Ford used these colors for years and years.

If there are only 3 wires then some one has combined the Ground wires which is OK, BUT......their splice may have come apart so sending unit ground was lost.

Gauge wiring is like this:
5volt pulse------Gauge in dash----------(yellow/white)--------------Sending unit in tank--------Ground

The gauge needs the sending unit's ground or it will show Full all the time, if you Ground the Yellow/white wire gauge will show Empty all the time
 

swamprat

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Joined
Aug 12, 2007
Messages
720
Reaction score
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Location
lexington KY
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1994
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Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
I have the cab off the frame sitting on 4x4 wood blocks between frame and cab, ground sounds about right
 
Last edited:

swamprat

Member
Joined
Aug 12, 2007
Messages
720
Reaction score
3
Points
18
Location
lexington KY
Vehicle Year
1994
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
I followed the bundle of wires running on the drivers frame to the inner fender. It splits into two connectors, looks like a 16 pin and maybe a 4 or 6 pin. can I test it here? Didnt really have time to work on it, Checked some grounds under the hood and under dash to see if I had left something loose after swapping pedals assembly.
 

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