Need help with gas tank ground!!!

[C10StartMstngAtHrt]

Hello all.. Thanks in advance for reading my post! I am a fairly new owner of a 1972 Chevy C10 Super 2WD long-bed with a 350/350 turbo. I'm sure its a fairly common occurance among all of you who have been here before but I honestly have no idea where to ground the gas tank in my truck. I replaced the original sending unit in the behind the seat, factory gas tank but it still continues to read "Full" when disconnected and "Empty" when connected. Is this a grounding problem? And if so, where exactly is the gas tank grounded? And I know it is completely unrelated but is it possible to change the heater core from underneath the hood with a factory air-conditioned truck? Thanks again to anyone that can help shed some light on this for me!

Adam

[BMERDOC]

The sending unit, much like most of the truck is grounded through the body/frame. What you have is a correctly operating sending unit. With the unit disconnected it should read way past full. With it connected (and empty) it should read empty. Can I ask a stupid question? Is the tank empty when you are testing it?

I haven't had experience with an A/C truck yet but I would assume that you would have to evacuate the system and pull off the box like you would to replace a heater core in a non-A/c truck.

Oh yeah... WELCOME TO THE CLUB!!!!

[C10StartMstngAtHrt]

LowGT, thats definately my next step I guess. Even though I replaced the float twice, I guess I should try using a plastic float as opposed to the brass OEM style float. Any other thoughts on the topic would be greatly appreciated!!! Thanks again!

Adam

[C10StartMstngAtHrt]

Bmerdoc, I do have at least a half a tank of gas when I attached the wire to the sending unit and its definately not a stupid question... Im sure there are a lot of people who would overlook that one lol. And as far as the heater core thing goes, my truck had the pump removed long before I got it.. I'm assuming the people who built the motor removed that to eliminate any power drain. They did however, leave everything else connected but left the system open to the weather and henceforth, giving me the joy of replacing every A/C part in the system lol. I was just simply wondering if the heater core could be removed from underneath the hood where the A/C box goes through the firewall before I dismantle it. And Thanks for the welcome to the club!

Adam

[LowGT]

Is their gas in your float on the sending unit? I'd pull it out and check it.

[BMERDOC]

When I put the sender in my 67 I had to get a new float because the solder around the seam was leaking and letting in gas. So try it again I guess.

I found an old thread about replacing the heater core. If you look at some of the trucks on here that have the heater box removed, the only way you can get it out is through the engine compartment. Here is that thread...

http://67-72chevytrucks.com/vboard/s...ad.php?t=69812

[ole dollor]

that link was for heater pickup only, i also think on factory a/c trucks you would have to pull the whole box from under the dash to get the heater core out and to check the evap. core also...

[ls1nova71]

Heater core is inside on a factory A/C truck. Its in the box directly below the glove box. You do however need to take the stamped steel nuts off from under hood side as the heater box has studs that go through the firewall and holds the outter box on.
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[SS Tim]

If you are going to pull the sender to check or replace the float you should function test it before reassembly. Sender in, key on check. Remove sender wire key on recheck. Remove sender, inspect wiper contacts, reattach sender wire, clip jumper from known good ground to sender body, again a clean ground. Key on recheck guage, slowly sweep arm or better repostion and let sit. That is the best way to function test the system by sweeping from full to empty in about 5* increments letting everything settle between movements. The other thing to do is run a resistance check on the sender. Its a 90ohm spec sender but I can't remember the specific numbers. Anyone have them handy?

[JointTech]

you have to pull the heater core from inside the truck. You have to pull that whole thing under the dash out. There are 3 nuts on the engine side of the firewall holding it in and if you dont know wherethey are you are going to need to drop the inner fender or youll never find it.
Took me 6 hours to remore my core. Still havent put it back in yet becasue once you pull that youll want to clean it all up.

Oh and youll have to buy new ducting. Its so old and brittle it will break and turn to dust if you touch it.

good luck. welcome to the party.

[BMERDOC]

Hmmm, shows what I know about an A/C truck!