Isuzu Rodeo Fuel pump sending unit

At approximately 50,000 miles the fuel gauge began reading empty when I knew it was more than half full. It was replaced under warranty. Then it occurred again at about 150,000 miles. The fuel indicator would go down much faster than fuel was actually being consumed. Sometimes it would work correctly, sometimes not. The problem continued to get worse, but I never had it replaced because I felt the estimates I was getting were too expensive when I could just estimate my fuel level by the odometer. Now, at over 300,000 the fuel gauge barely works at all and I'm also having issues with the check engine light coming on intermittently, or flashing. I didn't think the two issues were related until I read this, though I did have a mechanic tell me they may be related last summer when I had the catalytic converters replaced. Yeah, I know, I should have listened. Isuzu clearly had issues with this fuel gauge, maybe that's part of the reason they couldn't succeed in the most lucrative auto market in the U.S.

fuel pump sending unit said emtpy wind full of gas

A Firestone mechanic replaced the fuel pump. The gas gauge now reads empty all the time. The vehicle has been in the shop for almost 3 weeks and they still are unable to get the fuel gauge to work.

Edit:
After putting 3 different fuel pumps on my Rodeo, Firestone took the Rodeo to a shop that specializes in Isuzu's. The new shop fixed the problem. According to Firestone, one of their mechanics had inadvertently broken a wire that was not supposed to be broken. The new shop replaced a wiring harness and now the fuel gauge works.

Erratic fuel indicator, motor fan runs, engine light on. Have not had tome to repair

Fuel gauge shows empty when full & cold; when warm goes to 3/4 full no more no less.