Old or New Fuel Sender?

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73 MT Duster

73 MT Duster

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All,

I am putting a new tank, sender, lines ,and other parts on my car.

Attached are the pics of the factory (dirty) and aftermarket sending units.

I have tested them both with a multimeter. The "empty" reading is "80" for aftermarket and "88" for factory.

Any experiences that can help me decide?

I appreciate it....
 

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80 is closer to factory I believe it should be 10-73 ohms, in my experience mopar fuel gauges always read empty with a couple of gallons left.
 
I haven't seen or heard of a aftermarket sender being accurate. If the old one works use it. Do a sweep test with your meter though.
 
As you can see in your photo, when the float is half way up, the tank wall is set in for spare tire space. the float is half way up, but the fuel level is not. The factory Mopar sending unit is non-linear for this reason. the aftermarket sending units are linear. "Dart67" has been working on a programmable interface to use with the new linear gauges. When it becomes available I am sure he will let us know. It is still a work in progress, and there will be a bonus with his set up compared to the others. :D
 
Had the factory sender in my demon and about a year after the resto it went, bought a aftermarket one recommend by guys on here, supposedly its the closest to oem for being a aftermarket, ive not been happy with it, my oiriginal sending unit showed exactly how much fuel, the aftermarket one seems to read 1/8 of a tank more than there is, i would love to locate a nos one.
 
Both senders have their pros and cons. The original sender would bounce the float against bottom of tank. Eventually wears a hole in the brass float.
Lift the side of the electric housing open to view inside. You'll likely find the board has shrank with age and now slack in the winding has let it lift away from the board.
The scrubbing contact should be shaped like top half of a bagel for lack of better description. When that wears into a 'C' shape it hangs the loose winding like a fish hook would.
The aftermarket sender of later design isn't as accurate and the half moon shaped electric housing will collect trash in the bottom of it.
 
10 ohms full 73 empty. Re use the old tank ring or it will usually leak , The new ones are junk.
 
I took the pics so I could show you what I was doing. I will decide which to use and do a final install.

Thanks everybody for the input and advice. I have been a reader on the board for a while. I am now at a point where I'm actually working on the car.

Thanks again...
 
When I replaced my sender and gauge both I put a 2 gallon can of gas in the trunk and ran the car till it quit to find out where actual empty was.
With the correct ohm aftermarket gauge and sender it ran out of gas about 2 needle widths above the empty mark on the gauge.

Now I know.
 
halifaxhops said:
10 ohms full 73 empty. Re use the old tank ring or it will usually leak , The new ones are junk.
Click to expand...

when i did mine (i replaced the float which had cracked) i re bent the shaft and ended up at 10 and 70
perfectly dry i started adding fuel in measured amounts and it is quite close now.
2 measured gallons hit 1/8th
8 gallons 1/2
 
ir3333 said:
71DodgeDemon340 said:
Had the factory sender in my demon and about a year after the resto it went,

what went wrong with it?
it is just a mechanical variable resistor and i don't see how it could fail?
..did the wire come off?
Click to expand...

I wish i knew, it wasnt reading one day, grounded the plug and gauge went to full so i knew gauge was good, ground strap was tight and everything seemed right, i just figured the sender contacts were wore, maybe i should of kept it, ill have to look and see if i did
Click to expand...
 
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