'96 suburban fuel gage problem

this weekend my dad and i had to bring down my mom's suburban gas tank down because the fuel pump filter was soo clogged... now when we put the tank back in, the acceleration was a heck of a lot better, but then i noticed a problem. the fuel gage on the dashboard indicated that the fuel level in the tank was alllll the way full, i mean off the chart full, past the "F"... even tho we had only put about 50 dollars which is about 3/4 of the tank. my dad thought that when we had put the fuel pump back in, the lever that determines how much gas is in the tank was stuck and if we went over a few bumps in the road, the lever would get loose and fall to its normal position. we began driving and preformed a HARD and SUDDEN stop at a streetlight. at that point the gas level came to the position which it should have been, at the 3/4 level. but after about 3 seconds, the guage returned to its previous position, way past the "F"...... now before we take the tank down again, i wanna make sure we're not going to waste our time. do you guys think its a faulty cable on the fuel pump? if not what else? thanks.

Did you reconnect the ground wire to the frame? Was that connection clean? Many people forget to reconnect this wire and it can cause all kinds of stupid, hard to trace problems.

My 99 sub just started exhibiting the same problems with the gas guage. Mine has the 40+ gallon fuel tank, and my tripometer shows 350 miles, so I know it's near or below 1/4 tank, (cuz it don't get very good gas mileage.) The gas guage will fluctuate between 3/4 and full while I'm driving. When it's in park and the engine idling, the gas guage pegs out over full. I have never pulled the fuel tank, thus I haven't disconnected any wiring. A ground wire is mentioned in the above post. Does anyone know where this ground wire is located? Thanks in advance for your input.

The ground wire generally runs from the frame to the top of the sending unit (on top of the fuel tank). It's just a wire or metal fabric strap to ground the sending unit, since the tank is plastic and cannot provide a ground for the electrial components.

What year is the original post, cause my 97 has a steel tank with a plastic cover on the bottom of the tank that falls off when the staps are removed.

When I pilled my 97s 42 gallon fuel stockpile, the arm that connects the float to the actual gauge sending unit, in the tank, was loose and so brittle from the heat, that part of it snapped off. That could be causing the incorrect readings if the float is pushing the sending device only one way at times. I repaired mine with tie wraps and so far is working fine. You may want to read my thraed "Suburban Fuel Pump" in this Forum, on page 13 or 14 dated 10-21-04 and you'll get an idea of what's happening in your tank!

The other thing to watch out for is the in-tank filter or "sock". If you re-install the sending untit with that sock in a different position it will interfere with the gauge float. This happend to my Mom's Riviera, and it showed a 1/4 tank and she was empty.

Also these guages seem to stay on full or above for about 200 miles. My kids always find it amusing when the gauge reads almost full and it will take $30.00 bucks to top it off, I'm not laighing! :mad:

My '96 burban has a 42 gallon tank and even when the guage is on F, I can still top it off with another 13 gallons - Then it gets as you stated off the chart.
It has always been like this for me. I got 144K miles on it.

I did have this problem with My pontiac after having the tank replaced. They had to drop the tank and reinstall the guage float - The screen filter was interferring with it.