Fuel Gauge

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Paul King

Paul King

MrPJK
Joined
Jul 2, 2019
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Ontario Canada
Hi ,when i fill my tank with gas the gauge goes to full 10-15 miles down the road it drops to empty .the sending unit is new .the other gauges work properly ,could it be the voltage limiter .any one else have this problem ,Thanks for any help
 
More than likely its the new sending unit the new reproduction ones are garbage.
 
You can test the gauge by taking a ground wire and putting it in the sender plug. But if it goes up to full then drops back down its probably the sending unit or a bad ground. Do you have a ground strap on the line?
 
dartfreak75 said:
You can test the gauge by taking a ground wire and putting it in the sender plug. But if it goes up to full then drops back down its probably the sending unit or a bad ground. Do you have a ground strap on the line?
Click to expand...
Yes i do have a ground strap .if the ground is bad would it work at all,i guess it would work a bit
 
Does the new sender have a brass float? If sender is removed, test float to see if it is filling with gas.
 
Ground strap Could help. Here's what he's referring to.

groundstrap.jpg

s-l225.jpg
 
With my 66, the internal voltage regulator was bad. I replaced it with a 7805 digital regulator. That got the gauge working.

Due to the crap aftermarket sending units, when I fill it, it goes to about 7/8 full, when it gets to "E" i still have 1/4 of a tank.
 
66fyssh said:
With my 66, the internal voltage regulator was bad. I replaced it with a 7805 digital regulator. That got the gauge working.

Due to the crap aftermarket sending units, when I fill it, it goes to about 7/8 full, when it gets to "E" i still have 1/4 of a tank.
Click to expand...
Were can i get one .
 
dartfreak75 said:
You can test the gauge by taking a ground wire and putting it in the sender plug. But if it goes up to full then drops back down its probably the sending unit or a bad ground. Do you have a ground strap on the line
Click to expand...
You can do as Dartfreak75 said BUT only for a second as the guage will burn out if fully grounded. MANY posts here about guages.
 
Watch this video.


there are tons of these videos. They are very easy to understsnd
 
Last edited:
The general "flow."

1...Wiring. Wiring is always on your mind, how old are these girls. Bad connections at the cluster PC board for one
2...Bad instrument voltage limiter regulator

3...Bad sender or poorly calibrated aftermarket replacement sender.

4....Poor sender to tank ground

HOW TO START. One is to see if system OTHER than sender is OK. Two ways to do so. One way is to separate kick panel connector which goes to tail harness, ID the sender wire and use a decent digital meter to check resistance of sender. "Whatever that reads" interpolate that to what you think gauge should read. Here are the test resistances:

c-3826-jpg-jpg.jpg


Second to this is get on egag or an electronics supplier and buy some test resistors, or obtain an old rheostat which will cover that range Both fuel and temp and oil if equipped gauges should read the same with same sender resistance.

This should give you an idea of "which half" of the system is bad--sender or gauge system
 
What you seeing is how all the aftermarket fuel senders work. You can pay big bucks for an oem rebuild, or get a Meter Match. Cruiser just did a meter match on his car. I loaned him a calibration box I made. Lots of threads on this. If you decide to do a meter match let me know if you need help.

if you still have your oem sender keep it. Those are hard to come by for rebuilding.
 
Meter Match, yup. Evidently they were bought out and now considerably higher in price.
 
$84.00. OUCH!!!

I'll just keep using my trip meter to keep track of miles. Mine mostly works so its good enough for me!
 
My dad drove his dart 200,000 miles without a fuel gauge. 200 miles then fill up. He only ran out of gas once.
 
$84 for a Meter Match!!!!!???? Wow, mine was $40 a couple of years ago. Almost worth just getting an oem sender rebuilt now.
 
If I overlooked someone else saying this, I apologize. If the IVR was not working, I don't see how gas gauge would work at all. Not only that, but the temp and oil pressure gauges would not work either. The IVR feeds power to all three of those gauges (at least in my 69). I can think of one way to see if it is a grounding problem. I would use a length of wire with an alligator clip on each end. I would clean off a spot on the Fuel Supply Tube next to where the ground strap connects to it then attach the alligator clip on one end of the wire to that spot. Look at the right side of post #6. Then attach the other end to a KNOWN good ground. Do this in a way such that the wire won't come off during a test drive. If you have a decent multi meter, test this new circuit for continuity. That way you will know the temporary wire makes a good ground. Then turn the key to the ON position. If the IVR, gas gauge, sending unit and all wiring (to include the ground) are working, the gas gauge will work. Then take it for a test drive. Hopefully the gauge will work. Try that for a few days. Then take off the temporary wire. If the gauge starts acting up again, I believe you can chalk it up to a bad ground.
 
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