Thanks Bartamos.
1. When sender was out of tank on bench with nothing attached, ohm meter was set to 200 ohms with lead of tester on center tap and one on the flange where the ground wire was connected. I get a reading at empty of between 2.3 and 3.3. As I slowly move the float up towards full, the ohm meter starts to rise and immediately goes to 1. I'm assuming this means a bad sender. I was confused when I put the sender back in the truck and had everything hooked back up and with the key on, tested the sender again and got an ohm reading of 29.7, which would have been correct because the fuel tank is full. Sounds like this is an erroneous reading, though, based on what you said with wires being attached.
2. With power on and sender wire disconnected from gauge, gauge still reads empty.
3. Following this step, gauge stays on "E."
I'm going on the assumption that the sending unit is faulty and have ordered another one. When it gets in, I'll see if that fixes the problem. If not, then I guess it's on to the fuel gauge. I really hope it's the sending unit. I'm tired of contorting my body under the dash.
Appreciate all of the help.
Darrell
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.
