Sending Unit Resistance
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Sending Unit Resistance
Just curious what the resistance is supposed to be on the sending units for 70 vettes. I had a look at mine last weekend while I had the tank out and stamped on the side is 90 ohms. I can put $15 worth of gas in the tank and the gauge reads full. But I look in the tank and it may be around 1/2 to 3/4 tank. So, is it possible that I have the wrong sending unit in the tank? Just curious.
Thanks for any thoughts or ideas.
Thanks for any thoughts or ideas.
Melting Slicks
Joined: Mar 1999
Posts: 2,845
Likes: 2
From: Apex NC
Hey Eddie, the sending unit should be at about 90 ohms when full, and go toward zero ohms when empty. You may be able to bend the arm of the float to decrease the resistance of the potentiometer so that the gauge will read correctly at partially full levels. Give it a try, but be gentle.
Shannon
PS - that new black paint job looks KILLER!
Shannon
PS - that new black paint job looks KILLER!
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Thanks for the compliment and reply Shannon. I had the unit in my hands last weekend. I didn't think of it or I would have tried bending it then. With it in the tank it may be a little bear to bend. I may give it a shot anyway.
I need to make a new sig pic since the car is about 95% together.
I need to make a new sig pic since the car is about 95% together.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
It could also be a corroded connection - adding resistance,
or the wiring can start to corrode in the jacket.
I woudl pull the wire off at the sending unit and check the
resistance with a digital volt meter. If it reads 50-60 Ohms
and your guage says 'full' - you'll have to start hunting for the extra resistance.
If it reads 90 Ohms with 15 gallons - then bending the arm
would be appropriate.
Isn't it great to be at the point of fixing little annoying things ?
You KNOW you're almost done.
or the wiring can start to corrode in the jacket.
I woudl pull the wire off at the sending unit and check the
resistance with a digital volt meter. If it reads 50-60 Ohms
and your guage says 'full' - you'll have to start hunting for the extra resistance.
If it reads 90 Ohms with 15 gallons - then bending the arm
would be appropriate.
Isn't it great to be at the point of fixing little annoying things ?
You KNOW you're almost done.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
You need to do a search on this one Eddie. 
I posted testing mine before reinstall and could not get a repeatble resistance reading. But the gauge worked fine before removing so I just put it back in. Then someone with more ambishtion than me posted the same problem at first dry and again when submurged. So he removed the tin cover and cleaned the resistor to get a sucessful reading. I figure they're only about $70 and I will replace it if needed.
I read now you returned yours to the tank. Well it shouldn't take much to remove it again once all the fuel is drained now that you know how they come apart. Quanta (www.GasTanks.com) carries most everything for repairs/replacement - seals, senders, filter screens, etc..
Good luck. cardo0
I posted testing mine before reinstall and could not get a repeatble resistance reading. But the gauge worked fine before removing so I just put it back in. Then someone with more ambishtion than me posted the same problem at first dry and again when submurged. So he removed the tin cover and cleaned the resistor to get a sucessful reading. I figure they're only about $70 and I will replace it if needed.I read now you returned yours to the tank. Well it shouldn't take much to remove it again once all the fuel is drained now that you know how they come apart. Quanta (www.GasTanks.com) carries most everything for repairs/replacement - seals, senders, filter screens, etc..
Good luck. cardo0
