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Fuel Tank Sending Unit Question

tnfastback

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Should I use my original sending unit in new gas tank or replace it with a new one. Some say the new units won't read correctly?? I have a new one purchased from Spectra, but still have my original also.
 
If it ain't broke, don't fix it!
If it works good, use it!
Why change horses in the middle of a stream?
You get the idea? Good Luck
 
I'm with the "if it's not broke don't fix it", but there is a lot you can compare between the new one and the original. Get a ohmmeter and compare total resistance between the two and the difference in resistance at the different angles of the arm. Also compare the shape of the two to make sure they are actually shaped the same. My original in my 70 Bird was not able to be saved therefore I have spent endless hours trying to make the new one accurate. The best I have been able to do is get it where I have about a gallon left when it shows E, and when the tank is completely full the gauge shows about a needle width below F. If I make it show F it will run out of gas before E. The cluster was professionally done and calibrated by Redline Gauges and there is nothing wrong there.
 
I'm with the "if it's not broke don't fix it", but there is a lot you can compare between the new one and the original. Get a ohmmeter and compare total resistance between the two and the difference in resistance at the different angles of the arm. Also compare the shape of the two to make sure they are actually shaped the same. My original in my 70 Bird was not able to be saved therefore I have spent endless hours trying to make the new one accurate. The best I have been able to do is get it where I have about a gallon left when it shows E, and when the tank is completely full the gauge shows about a needle width below F. If I make it show F it will run out of gas before E. The cluster was professionally done and calibrated by Redline Gauges and there is nothing wrong there.
That reminds me of my first car, a 69 Ford Fairlane that had been rear ended. It had a 10gal. tank with a 20 gal. sender, the gauge read from 1/4 - 3/4's.
 
test the new one out by plugging it in outside the tank. if it reads correctly. good to go
 
I just went through this on my Belvedere. The FSM says ohmmeter should read 72 plus or minus 12 at empty and 9 plus or minus 1 at full. The old crusty one was all over the place on OHM readings and I know it was giving me some weird readings when I last drove the car before tearing it apart. Ordered a new one through Summit and tested it this afternoon....77 ohms empty, 8 ohms full. The sending unit was something like $39 and had good reviews....time will tell if it's good or not.
 
Can't disagree with that.....unfortunately my old one crapped out and I didn't have an alternative. I've seen enough feedback on this site to know that I preferred my old one working, but it wasn't in the cards for me. I won't know until the spring how my aftermarket one works.
 
Yep.. I'm in the same boat.. Repro in the Bee and OE in the Bird. When I get life settled down here again after Talladega I plan to do some work to make repro's correct to the non-linear OE readings so people can have correct senders again.
 
I’m pulling my OE one this weekend to check it out. I need one with a 1/2” pickup to use as a return line. Was looking at this one.
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As others have posted, to my knowledge nobody makes a decent reproduction one.

On the other hand, if that original one of yours is 3/8", I'd be happy to relieve you of it. :)
 
As everyone has stated, none of the reproductions currently available are accurate. Testing the units to observe that the desired levels of Ohm resistance does not give a factual reading of the unit at various levels of fuel.

Some of the units are so poor that the plating will begin to rust immediately after installing them into a tank. The Spectra units seem to hold up although they are not accurate.

Seeing that you are replacing the tank, make sure that the sending unit lock ring is the correct thickness. There are numerous threads out there concerning the new lock rings furnished with the new tanks that are not thick enough. Reuse the original lock ring or purchase a new one from a reputable vendor who sells one of the correct thickness material.

Personally, if I was replacing a tank, I would replace the filler tube grommet; reuse the sending unit if operable, just replace the sock; reuse the lock ring and replace the fuel tank studs and nuts and all of the rubber lines.
 
Halifaxhops was selling new OEM sending unit lock rings. At least on FCBO and I am sure hear as well. I bought one a week or so ago.
 
I have a Spectra and it's been working great for two years. Then this summer after a fill up it stayed on "Full" much longer than normal. When it finally dropped to "3/4" I filled it up and it took 9 gal. Something is getting out of calibration.

It's acting the opposite of what most people have trouble with.
 
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