f the other gauges work, then replacing the IVR with an aftermarket replacement won't help, and actually slows down the gauges at start-up. As said previously, if the float isn't full of gas, then bending the float arm or MeterMatch is probably the solution. If you need to buy a new sender go with NPDs best (call them). None of the replacement senders match the OEM according to Rick , the owner of NPD. The following may be of interest:
Edit: I removed the diagram and data from below, because with further testing done today, I found that both the OEM and aftermarket IVRs bring the gauges up to their operating ranges in about the same time. That was unexpected given the higher voltage for the OEM version just after start-up. What I found interesting was that the aftermarket IVR gave lower values when on high- about two needle widths lower. This may take a bit more investigation, because the OEM version of the IVR was outputting 5v continuous on high, but I'm not yet certain if the aftermarket IVR got loaded down and dropped it's output when on high, because it was also 5v ...when on low.