C-1 gas sending units

[Lonnie Johnson]

I know reams of information have been written about this subject, but I have what I consider a unique situation with my '62' gauge.
It stays on empty even when the tank is more than "empty". So, I remove the gas tank cover and pull the sending unit, turn the key on and run it through it's range and the gas gauge reads perfectly. Put the cover back on and the gauge is working wonderfully. Start the car, and the gauge goes back to empty and will not move off of it, until I repeat the procedure describe above. Start the engine, yep, same story. Have tried running an independent ground, etc. and to no avail. Has anyone ever had this type of situation before, and if so, can you suggest a remedy?
Thanks for any help you can give.

LonniezC

[G B.]

Yes, I had a similar problem

The brass float had a hairline crack and was filled with gas. I had to replace the float.

[Roy B.]

Re: C-1 gas sending units

You added a separate ground to wear from wear?

[Lonnie Johnson]

Re: C-1 gas sending units

Directly from the negative terminal on the battery to the sending unit base.

[Roy B.]

Re: C-1 gas sending units

Ok so your betting the sender unit base is grounded to the tank by the screws but is the tank grounded?? Many assume it is but not always . Run another wire from sender or gage ground side to some other grounding area and see if that cures your problem.Let use know. Remember you hear other talking about their engine starting when cold but not when hot.( they are loosing ground. )

[Christopher R.]

Re: C-1 gas sending units

He grounded the sending unit by running a dedicated wire from the battery negative terminal to the sending unit. Check (with a multi-meter) that it's making a connection. But assuming it is, it must be then that the float doesn't. The float has a hole and doesn't float.

You can buy the floats separately from the unit for around $5.

[Lonnie Johnson]

Re: C-1 gas sending units

Chris,
Yes, the connection is secure, float is new since I suspected it orginally. Just to be on the safe side I pulled the float and checked it and it is fine. The goofy part is that when I pull anything apart on this unit and reassemble it, the gauge works fine until I start the engine, then it quits immediately, and will not work again until I tinker with it some more. I've repeated this process several times with the same results. Has me scratching my head, since I can't see why the engine running would have anything to do with the gas gauge.

[Terry D.]

Re: C-1 gas sending units

Lonnie

Since it starts acting up after you start the engine have you checked the wiring on the start side of the ignition switch? Maybe something is loose or touching where it should not be. Just a thought.
Terry

[Lonnie Johnson]

Re: C-1 gas sending units

Well Terry, you're "sorta kinda" on the right track! I did check the wiring, and found that some time prior to my owning this car since 1973, "Bubba" got smart? and decided to do a little rewiring on his own and switched the brown sending wire unit and the black/white ground wires back over close to the gas tank filler pipe area. Also, found a suspect terminal on the sending wire lead so replaced that. Problem solved. What I can't understand is why someone would do such a stupid thing, but I guess Bubba's last name must have been Murphy, of "Murph's Law", eh?
Thanks to all of you for your help, not sure I still understand why the engine running had anything to do with this, but maybe it was partially vibration, just don't know!