Been working on a '97 Crown Vic 4.6 PI.
The problem's the fuel guage... shortly after taking off, the guage just slowly drops to bone dry. It takes its time like I'm getting about 8 gpm (not mpg). Sometimes within a mile or so. After a while, it'll come back up... slowly.
I've changed the guage, anti-slosh circuit, and the sending unit/float.
It only happens on the road, I let it idle for hours and nada.
I'm sure the slow drop/rise is a function of the anti-slosh, so I'm thinking (now) of a bare spot on a wire (haven't found it yet).

Any thoughts? It's been a recurring nightmare.

Thanks...

 

Does the problem only happen with a low tank or even with a full tank

 

Thanks for the reply.

I've seen it happen anywhere from 1/4 to 3/4 tank.
Haven't tried a full tank. I could, I guess.