Test in order, exactly as described.
1. Sender ohm test is done with NOTHING but the tester hooked up to it. One lead of tester on the center tap and one lead on the flange. Out of the tank and operating float by hand. 0-30 reading, sender is good. If your meter is set correctly (200 ohms) with leads connected in prober places on the meter and you do this test and it does not read approx. 0-30 ohms, the sender is bad.
Sender tests good? then:
(sender re-installed)
2. Power ON:
Disconnect sender wire from gauge and hold in air, gauge goes to "F", good gauge so far.
3. Power ON:
Take off sender wire on back of gauge, hold off to the side. Attach a jumper from the sender terminal on the gauge to GOOD KNOWN ground. Should read "E". That is the same as taking sender wire off at sender and touching it to a GOOD KNOWN ground. That second form of the test also verifies that the wire leading back to sender is OK. Goes to "E", gauge is good.
The gauge itself MUST BE GROUNDED. Depending on design, that usually is a lug on the back touching the gauge cluster metal and the gauge cluster metal touching the dash and back thru /body/chassis/motor... to battery neg post. This is a common place to lose ground as well as at sender. losing ground is Number one cause. But we shall see.
A gauge reading "E" may have the sending wire touching ground somewhere along the line. Especially if sender tests good. You must have a brand new, continuous wire from sender center tap to gauge "S" terminal. Period. No matter what's wrong right now.
There are other procedures and sequences to test fuel reading system. You may choose any system you like, but I don't know about those for sure.
You are at a point, in my opinion, that you have not proven anything.
