'68 Barracuda -wire to fuel tank sender

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Dave NEO

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my understanding is that wire to sender is a ground wire. is that correct? thnx
 
No. Wire to fuel sender is a feed to the sending units variable resistor from the gage. If you run that wire directly to ground the gage will read full all the time.

The sender is grounded thru a clip that attaches to the metal fuel feed tube on the sender and jumpers over the rubber sending unit feed hose, and clips back to the metal chassis fuel line on the other side.

Screenshot_20190914-132612_eBay.jpg
 
It acts as the ground for the fuel gauge but is not an actual ground wire. It has variable resistance to ground depending on where the fuel level is.
 
so...it should read 12V with ignition on? mine does not,; am thinking it may have grounded out somewhere..suppose it runs from gauge on dash?
 
seems I read their is a connector of some sort in left kickpanel , does that sound right? BTW I don't see a ground jumper of any sort in the fuel line.
 
the wire going to the sender is a 5 volt reference voltage that pulses on off.
Yes there is a connector for it behind the
left kick panel. at the tank there is a short
piece of rubber hose connecting the fuel line to the sending unit and fuel line is at chassis ground potential and the sender isn’t. therefore the sender and fuel sending unit are insulated
from each other by the short hose hence the reason you need the ground strap shown above to give the sender a reference to ground.
 
yes thnks - forgot gauges are 5V - can't get any volt reading whatsoever from the sender wire. Am going to install a temporary ground strap and see again if I can get any reading at all from sending wire with ignition on.
 
Check the posts on the back of the guage cluster. With key on you should read 5v (give or take) on both posts with the sender wire off the sending unit.

Does your factory temp guage work correctly?
 
yes, it does- I will need to find out how to at least loosen up/tilt in the gauge cluster.
 
You should be able to reach the posts with guage in place. If you try to pull the cluster you have to discount the ammeter wires and stand a greater chance of damaging something.

That your temp guage is working shows that your IVR (instrument voltage regulator) is functioning so that is probably not the issue
 
You should be able to reach the posts with guage in place. If you try to pull the cluster you have to discount the ammeter wires and stand a greater chance of damaging something.

That your temp guage is working shows that your IVR (instrument voltage regulator) is functioning so that is probably not the issue
Sorry for jumping in here ,I have the same problem .Temp gauge works but the fuel gauge stays at half full.Great info.Thanks
 
all the time key in or not? Or only reads empty to 1/2 full? what have you replaced lately?
All the time. I bought the car knowing the fuel gauge didn't work and it read empty.I put gas in it and the gauge went to 1/2 and never moved since.Someone ran a wire from the sending unit were you plug in the gauge wire to the frame ,not sure why.i removed it .
 
If you take the wire to the tank sending unit and disconnect it with the key on and gage drops to empty, then take the same wire and jump it directly to a chassis ground and gage goes to full, then you can rule out the gage being an issue.
 
If you take the wire to the tank sending unit and disconnect it with the key on and gage drops to empty, then take the same wire and jump it directly to a chassis ground and gage goes to full, then you can rule out the gage being an issue.
Okay thanks so much for your hep appreciate it
 
You can do the same thing with the temperature gage. Unplug sender with key on, it should go to cold. Jump the sender wire directly to ground it should peg all the way hot. That rules out a temp gage being a problem. Using this method with both fuel and temp gages also tests the sending unit wires from the gage to the sender for opens or ground shorts to rule those issues out as well.
 
You can do the same thing with the temperature gage. Unplug sender with key on, it should go to cold. Jump the sender wire directly to ground it should peg all the way hot. That rules out a temp gage being a problem. Using this method with both fuel and temp gages also tests the sending unit wires from the gage to the sender for opens or ground shorts to rule those issues out as well.
The temp gage seems to work okay,but I will test it anyway
 
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