Gas sending unit float

[David K.]

I tried doing a search without success. What is the proper height of the float. Maybe a demension from the bottom of the mounting flange to the top or bottom of the float. My tank is roughly 1-2 gallons down from full and the guage reads 5/8 tank. I have the sending unit on the bench now looking it over. On an ohm meter, the sending unit, seems to be working as it should. Is there a good way to tell if the float is leaking? I hear no gas in it by rattling it. Yes, I am going to add an additional ground wire to the sending unit as well. Oh, the car has new fuel sending unit, wiring harness and restored guages, that were to have been recalibrated when restored.

[David K.]

Re: Gas sending unit float

Found my problem, got it.

[Christopher R.]

Re: Gas sending unit float

Move the arm through its range of motion and measure the resistance. Check the archives, but I believe a C1 gas gauge sender goes from around 0 to 90 ohms. Not 100% sure. If that checks out, your sender is good.

If it doesn't read correctly at the gauge, you'll need to bend the arm to make it read right. Make it a few gallons pessimistic so that you'l have a reserve. If you're down 1-2 gallons now, make it read full.

Check the float by shaking and listening to it. You can also put it in hot water and check for bubbles. The hot water will expand the air inside the float, pressurizing the float.

If you need a new float, you don't need to buy the whole sender. If the usual Corvette parts suppliers don't sell the floats separately, The Chevy parts suppliers do. Should be around $5. I believe the 55-57 Chevies had the same float. Many other years too. This float is quite common.

Make sure you put a new sock on there too.

[Roy B.]

Re: Gas sending unit float

Found my problem, got it.

OK what was it

[Pierre J.]

Re: Gas sending unit float

I tried doing a search without success. What is the proper height of the float. Maybe a demension from the bottom of the mounting flange to the top or bottom of the float. My tank is roughly 1-2 gallons down from full and the guage reads 5/8 tank. I have the sending unit on the bench now looking it over. On an ohm meter, the sending unit, seems to be working as it should. Is there a good way to tell if the float is leaking? I hear no gas in it by rattling it. Yes, I am going to add an additional ground wire to the sending unit as well. Oh, the car has new fuel sending unit, wiring harness and restored guages, that were to have been recalibrated when restored.

Dave, if you want to avoid problems with leaky float in the future, install a Stewart Warner part # 836092 float. These floats are made of a solid material and won't leak.
Pierre

[David K.]

Re: Gas sending unit float

I am not sure that I found the problem as much as I gave up. When I redid the car, I replaced the wiring harness and the gas sending unit. The new unit, never, ever gave me a full tank showing, even though I had a full tank. So, I just put the old sending unit back in. It seems to be working ok. I filled the tank, syphoned 8 gal. out and showed 1/2 a tank. put in 4 gal. and showed 3/4 tank and when another 4 gal. was in I now showed a full tank and the tank was in fact full. Metering the new sending unit shows it to be functioning ok, so it must be in the float setting. The float also tested good, with no leaks in it. Like I said, did I fix it, or just give up?