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Here's the problems. Gauge reads half and will slightly go down. Gas tank has 85-90% fuel. Gauge should read higher.
I have tested the gauge with 3v and it goes to full, so that's good. When I put my ohm meter on sending unit wire I am currently reading 16.4 ohm ( on the tank). I checked sending unit wire on the gauge and also am reading the same ohm value. I had to run a new wire from ign to the volt reg. Any help would b greatly appreciated. Thanks.
 

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Your gauge needs adjustment. Or, the IVR is off. 16.5 ohms should give a high high - but not full - reading. Stock senders are about 73 ohms (empty) to 10 ohms (full). Less resistance causes the gauge to read higher. Simply shorting the sender wire to ground should cause a full-swing of the gauge.

I would suggest: First, check if the other gauges are reading properly. If so, then the IVR (instrument voltage regulator) is likely working properly, and pulsing from 0v to battery voltage for an average voltage of ~5.5 to 6 volts to the gauges. This voltage test must be done with an analog volt meter, as a digital version will just display constantly changing garbage. The IVR works like a turn-signal flasher, with a rapid ON/OFF for the average voltage. Obviously, if the other gauges appear to also be low, then the IVR and power wires would be the first focus of attention.

If that seems fine, then pull the gauge to make adjustments with the two adjustment points. There are two holes in the back of the gauge. One slightly closer to the center or studs than the other, and is closest to the needle pivot point. Adjust in that hole first with no power to the gauge to set gauge "zero" or in this case, just below E. The adjustment is made with a small flat screwdriver blade to tweak the little teeth in the hole to each side.

Then adjust the outer hole (closer to the needle tip) with power and signal to the gauge to set the current actual reading. Re-test both settings and re-assemble.

David
 
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