Had new fuel pump put in, now fuel gauge won't work, registers right when you start but goes to e immediately

your car will not run on E85.


https://fuelandfriction.com/weekend-warrior/e85-dont-do-it-unless-you-know/

Check for a frayed wire touching metal and grounding out. The gauge works on resistance and it registering full indicates a short to ground. Either that or your gauge itself is bad.

put foot flat to floor DONT pump the accelerater pedal turn on ignition turn over engine as soon as it starts take foot off pedal happy motoring..

There are two basic reasons for not starting - no spark or no fuel, both of which are controlled by the ECM. You need to check error codes and these items - for the spark, test it at the cylinder 1 sparkplug; for the fuel check the pressure (if too high or low, problem!).

Eewww. That's not good. And you're not going to like what I say. I think you bent the fuel gauge sender unit, or misaligned something when you put it back in tank. Try unplugging the connector and plugging it back in. See if that helps the gauge to register right. Here's a quick check to see if your dash gauge is working right: Unplug connector again at tank and use a jumper wire to ground the dash gauge sender wire. With key turned to on and the fuel gauge wire grounded, the gauge should jump up to half or full. If it does, there's a problem with your sender unit in the tank.

check the fuel pump pressure with a gauge to see if has the right pressure and you may want to check the fuel pump relay to see if it is good .the pump may not be keeping the right pressure after it gets hot . if the pump is working i would try the relays .but use a repair manual for the right pressure readings .

I had a Grand Prix one time (basically the same car) that had a problem with the fuel pump harness. This harness plugs into the top of the fuel pump as you know, and into the floorboard underneath the car. Check the floorboard end for corrosion or broken wires.

sounds like its not working properly, the fuel pump pumps or it does't, then goes to regulator this is where pressure is adjusted. check fuel pressure with gauge, sometimes even new fuel pumps don't pump enough fuel. most fuel injected cars have over 50 pounds pressure.

Likely you did a bad thing to the tank float when working on it If so, it will need to be taken down (again) and checked. First though check that the gauge is getting power at the attachment harness (pump and power side should have a voltage pulse and good tank grounding.)

Check the fuel pump relay:


It is below the park lamp relay.