Did you test the sending unit before install? It should measure from around 10 ohms to 73 ohms for a OEM sending unit. The aftermarket sending unit many times are much less accurate but you should at make sure it works before install because sometimes you can bend the tabs to make some adjustment. Go on youtube on how to test. The wire at the sending unit can be momentarily grounded to see if the dash gauge moves to full. If it doesn`t the dash gauge, limiter or wiring could be the issue. My car has a ground strap on the fuel line where the rubber hose connects the sending unit and the metal fuel line.