Fuel Sending Units

[Warhorse]

Ok, I haven't found a topic on this but it's gotta be in here somewhere. I'm having a bad fuel sending unit experience. I have just about finished the restoration of my '68 Charger, with just trim and stuff to go and I've had her out on the road for a shakedown drive already. My sending unit issue began when I added fuel for the first time. I put in 10-gal of Av Gas and a leak around the sending unit locking mount ring began immediately. I siphoned the fuel out, dropped the tank and found the locking mount ring completely loose. Note that someone else actually installed the fuel system. What I discovered was that the locking ring was a very cheaply made stamped piece that didn't even fit the locking ring wrench tool properly. The locking ring was too thin as well. I found two locking rings available at Classic Industries: one was this same cheap part I have: Part# MF291 "Stainless steel" and the other is an OEM type Part# MF292 "Zinc." This latter piece is the correct piece, stay away from the other one. Note that the correct piece costs $5 more. I installed this correct piece along with the original gasket and it tightened nicely using the locking ring wrench. I had a good leak check and installed the tank. I poured in the rest of the fuel and started the engine: now the fuel gauge registers just a tick above empty (should be over 1/2 tank). In what could be another forum subject, I fabricated a test box using an original gauge cluster plug and tested the fuel gauge on the bench and it tests good: 73-ohms FULL/10-ohms EMPTY (per the manual), so the fuel gauge is good. I measure 50-ohms at the cluster plug going back thru the wiring and sending unit; I would expect around 30-ohms for 1/2 tank. Dang, looks like a bad sending unit! After my experience with the cheap locking ring and some other "cheap" parts I've run into along this resto journey, I'm wondering if I have a "cheap" sending unit that is not worth its weight in tin. Has anyone else run into crappy sending units? Are there ones that can be recommended?
thanx...

 

[GearAddict]

Might want to check sending unit to ground resistance at the tank to ensure that it is not just resistance buildup from poor crimp connections or worn contacts.

I'm chasing the same thing myself at the moment... it's pretty easy to end up with 20 ohms of additional resistance with old/corroded contacts.

 

[Bigal75]

I have a good one out of my 67 RT I would be willing to part with. Worked perfectly. Let me know.

 

[Icecobra]

Is the fuel sending unit new or original?

 

[Warhorse]

Actually it is all brand new stuff, sending unit, tank, lines, ground strap, you name it (Year One). I did check continuity to ground and it was good.

- - - Updated - - -

See above, all new stuff. I just get concerned when I see "Made in China" etc...

 

[Mopar-Charger]

Had the same problem with my car. I have a 1973 charger There's two versions of the fuel sending unit A and B? If you look it, the one you have has an extra vent tube on the face, and the other version of it doesn't.

You want this one http://www.amazon.com/gp/product/B000C7TWE6?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00

Not this one http://www.amazon.com/Spectra-Premi...4&keywords=Spectra+Premium+FG93a+Sending+Unit

My tank would leak around the ring with anything over 10 gallons. Swapped the washer, gasket, and even the tank. No dice. Finally decided to buy a new one ^ (got the B version instead of A) no more leaking. Happiest day of my life... :headbang:

 

[hunt2elk]

The new repoped sending units are nothing to write home about. Nobody can seem to figure out how to make them properly. There is a guy over on the Lift Off Hood Playground that has some nice ones. I got my last one from him and works great. It is good to know that someone is selling decent lock rings also. All the ones coming on newer sending units were also junk imo.

 

[themechanic]

The new repoped sending units are nothing to write home about. Nobody can seem to figure out how to make them properly. There is a guy over on the Lift Off Hood Playground that has some nice ones. I got my last one from him and works great. It is good to know that someone is selling decent lock rings also. All the ones coming on newer sending units were also junk imo.

I need a good one. How about a link or user name?

 

[hunt2elk]

I need a good one. How about a link or user name?

pm sent.

 

[65-440]

I got mine from right stuff detailing, hopefully no problems !

 

[CHR73]

I have same extra ventingtube whit my new sending unit and i check orginal dont have it .is it working right if i put some filling that hose ?

 

[themechanic]

The extra tube is a fuel return line connection to the sending unit. You can block off the fuel return line if you don't have one.

 

[dual fours]

The extra tube is a fuel return line connection to the sending unit. You can block off the fuel return line if you don't have one.

Make sure whatever you use to plug the extra tube is fuel friendly.