Fuel guage stuck on 1999 Ran Van 3500

I changed pump and float and it would be hard to bend the float. It was a Carter pump and the tank is 35 gallon unit. I put 10 gallons in and guage went to 1/8th of a tank and low fuel lite came on. I figured because of 35 gallons 10 gallons wasn't enough so I filled tank. The guage still read 1/8th and lite was on so I replaced pump again. The guage went up when I put fuel in but was slow. It read 3/4 full when I put 32 gallons in, I just figured electric guage no problem. Now after driving for 5 days and putting 35 gallons in it went to 1/8th tank and lite back on. Would this be a cluster problem?

Did the fuel gauge work this same way before changing the pump assembly, or did it work normal?

Did the fuel gauge work this same way before changing the pump assembly, or did it work normal?
From what I know it was fine before, this van has only 43700 miles on it but it has a wheelchair lift and probably sets at idle more than normal. I had to replace engine and exhaust. I saw where some guys say you canreset cluster but not sure on commercial vans.

If it was working good before I would suspect either a bad electrical connection at the sender, or it's a bad sender.

Press and hold the trip-reset button on the cluster while turning the ignition on, a self-test will start immediately. This might give you an idea if the gauge is dead or not.

If it was working good before I would suspect either a bad electrical connection at the sender, or it's a bad sender.

Press and hold the trip-reset button on the cluster while turning the ignition on, a self-test will start immediately. This might give you an idea if the gauge is dead or not.
I'm still waiting on the guy to bring it back to me. When I find the problem I'll be sure and update this post..Thanks