Fuel gauge still not working, What am I missing? Options

[john77]

With the ignition on the needle on the gauge lifts to E but goes no further despite the tank being full.

I pulled the sender, wired up a new ground and hooked up a new wire from the gauge to the sender and tested the sender manually by turning it upside down and then back. The needle goes from empty to full and back to empty. Just to double check I test the resistance, 0.2 ohms right side up, 89.9 ohms upside down (the range is 0-90 ohms).

So I put the sender back in the tank with the new wiring, switch on the ignition and... the needle rises to E and goes no further.

So I think maybe, somehow, the floats not lifting. So I pull the sender, fill a bucket of water, dip it in, and the needle on the gauge rises and tells me I have half a tank - or less or more depending how much I submerge it. In other words, the damn thing is working.

So I put it back in the tank and nothing, the gauge rises to E and stays!!!

What the hell am I missing here? It works in a bucket of water but move it a foot and put it in my gas tank and nothing.

John

[timothy_nd28]

The problem was with the sender unit. You measure 2.3 ohms between both terminals on the sender (with the sender installed on the tank). 2.3 ohms on this sender means empty tank. You then measured both pins to one of the mounting scews that fastens the sender in place. You reported back that the resistance readings was infinite. This shows that the sender is electrically isolated to ground, which is what I expected.

Again, the sender is installed, reading 2.3 ohms, yet you had 4/5th worth of gas in your tank. This was the issue. The gauge was only reading what the sender said. If you sender was reading 90 ohms, I'm sure your gauge would of read full.

The float on the sender is sitting at the bottom, and not floating. I'm not sure what's going on with that. 4/5th worth of gas should had the float pretty high up, and a reading 80 plus ohms. 2.3 ohms means the float is sitting or hung up at the bottom.

I'm not sure what you just did, but I'm afraid you may have just ruined the gas gauge, which happened to be the only part that was working. Your issues lay with the sender.

[john77]

The problem was with the sender unit. You measure 2.3 ohms between both terminals on the sender (with the sender installed on the tank). 2.3 ohms on this sender means empty tank. You then measured both pins to one of the mounting scews that fastens the sender in place. You reported back that the resistance readings was infinite. This shows that the sender is electrically isolated to ground, which is what I expected.

Again, the sender is installed, reading 2.3 ohms, yet you had 4/5th worth of gas in your tank. This was the issue. The gauge was only reading what the sender said. If you sender was reading 90 ohms, I'm sure your gauge would of read full.

The float on the sender is sitting at the bottom, and not floating. I'm not sure what's going on with that. 4/5th worth of gas should had the float pretty high up, and a reading 80 plus ohms. 2.3 ohms means the float is sitting or hung up at the bottom.

I'm not sure what you just did, but I'm afraid you may have just ruined the gas gauge, which happened to be the only part that was working. Your issues lay with the sender.

Yep, looks like the gauge is ruined, I pulled the sender and now when I invert it the needle just sits there. As an aside, the float is free moving, and was free moving in the water, so I have no idea why it's not floating in the gas.

Thanks for your time and patience on this Timothy, I appreciate it. I'll speak to the manufacture tomorrow and see what his prognosis on the gauge is.