[70gteeo]

I check (tested) my fuel gauge in the dash and it works. My sending unit in the gas tank stop working after 19 years. I got one from Ames and tested the ohems range is 1.2 to 92. This is for a 70 gto. I then hooked up the power wire and ground wires. When I moved the float the fuel gauge moved to each location correctly. Then I installed the fuel sending unit in the fuel tank. Installed the tank back in place and added 5 gallons of gas and the fuel gauge did not move from empty. That should be enough gas to move the float in the sending unit and register at least 1/4 to a little above. I am not sure what to check at this point?

[Bill Hanlon]

Were you using the same wire to test the system with the sending unit out of and in the tank? Gauge at empty in a system that otherwise tested OK means that the wire from the sending unit to the gauge is shorted to ground.

[Geoff]

Float arm on sender may need adjusting. Fill the tank & see if it reads full.

[JSPONT]

Check the ground and make sure it has a good one.

[70gteeo]

I used the ground wire from the sending unit in the same location on my car for the test outside the tank and when installed. So I will be draining the gas out of the tank again we all know how much this sucks. Go over everything again and install the unit and tank and cross my fingers it works this time. Thanks for the replies.

[Greg Reid]

Originally Posted by Geoff

Float arm on sender may need adjusting. Fill the tank & see if it reads full.

This...probably.
If the arm is physically bent too far up, the 5 gallons may not be enough to move it when it's suspended above the level of the fuel in the tank...and in that case, it will also not read full either because it hits the top of the tank too early.
I always make sure that the float is barely above the bottom of the dry tank.

[Jack Gifford]

These same symptoms drove me crazy as I finished up my GMC. I finally discovered a pinhole leak in the brass float.

[70gteeo]

I filled the tank up with another 5 gallons so now there is about 10 gallons in the tank. The gas gauge did not move off of empty. I drained the fuel tank and when I stood the tank up (fuel neck) pointing toward the ceiling a structure inside the tank slid toward the fuel sending unit area. It’s looks to be about 12-14 wide 2.5 height width not sure if it’s al the way around (enclosed). I have a CA car with EES system. The tank looks very clean on the inside. So it looks like I will need a fuel sending I got this one from Ames. Do you know where I can get a fuel sending unit made in the USA or one that is not Fargo Automotive crap? Also is this normal for a fuel thank with the moving structure or do I need a new fuel tank?

[connman]

Stupid question! Was it indexed in tank right? Did you accidentally turn it ?

[70gteeo]

I installed it fitting sending unit in the two slots where the tads are.

[Greg Reid]

Originally Posted by 70GTEEO

I filled the tank up with another 5 gallons so now there is about 10 gallons in the tank. The gas gauge did not move off of empty. I drained the fuel tank and when I stood the tank up (fuel neck) pointing toward the ceiling a structure inside the tank slid toward the fuel sending unit area. It’s looks to be about 12-14 wide 2.5 height width not sure if it’s al the way around (enclosed). I have a CA car with EES system. The tank looks very clean on the inside. So it looks like I will need a fuel sending I got this one from Ames. Do you know where I can get a fuel sending unit made in the USA or one that is not Fargo Automotive crap? Also is this normal for a fuel thank with the moving structure or do I need a new fuel tank?

Why do you think you need new sending unit? Does it still work when you move it manually? If there is a moving structure inside the tank, it sounds to me like that is your issue. Whatever it is may be obstructing the movement of the float.
I've never heard of anything that's supposed to be inside the tank like that. Can't imagine what that might be.

[Peter Serio]

There may be a baffle inside of the guy's tank. On the '70 and up GM cars they started to put in things cars to help gasoline vapors not vent directly into the air. There are some metal pipes in behind the rear seat in addition to the one that gives fuel from the tank up to the engine compartment. I would get one of those view-scopes & see just what has come loose inside the tank. Perhaps a new tank would solve this problem?

[70gteeo]

I think your right Pete it a vapor vent baffle. It’s the orig tank from 1970 so maybe it has just degrade over time. I am not sure that it’s hitting the float. If it moves that far forward it would hit the fuel pick-up screen. I did the testing in my garage filling the tank up with fuel cans. Yes I tested the sending unit not in the tank and the gauge in dash worked at all positions.

[Pepi]

Originally Posted by 70GTEEO

I think your right Pete it a vapor vent baffle. It’s the orig tank from 1970 so maybe it has just degrade over time. I am not sure that it’s hitting the float. If it moves that far forward it would hit the fuel pick-up screen. I did the testing in my garage filling the tank up with fuel cans. Yes I tested the sending unit not in the tank and the gauge in dash worked at all positions.

So just to clarify, this sending unit works when out of the tank and hooked up to all original wiring, but once installed in tank it doesn't?

I'd be checking float like Jack mentioned and that loose baffle.

[Peter Serio]

The only other thing I can think of is the tube the sender is made from; where they spot welded the pivot (which contains a metal enclosure with the resistor card). Perhaps that part is welded an inch to high up on the tube. As a 3D checking fixture the maker should have a tank cut in 1/2 so they can check the fit of their new sender as per a standard fuel tank. It would need to be made so that the arc of the float from low position to high position approximates the space inside of the tank. Plus or minus 1/2" If you can't find anything loose inside of your gas tank perhaps the new sender just doesn't fit the "space."

Sometimes I wonder what, if any, the quality control is on these cheap imported electrical parts? It's not like the company who is making this stuff really knows all about the car and how parts fit together or in this case should fit together so that they work properly.