Re: fuel gauge always full
Don't know what you are measuring but try this instead. (again the test procedures for this system have been covered many times in this forum)
1) Disconnect the pink send wire from the gauge.
2) Key ON (gauge should be reading "E" at this point). If not, gauge is toast or "S" terminal is shorted to ground.
3) MOMENTARILY jump the "S" terminal to the GROUND terminal on the gauge. (Note MOMENTARILY - just a touch is all that's necessary)
4) The gauge should read "F" momentarily. Yes or No?
5) If yes -- the gauge is good. If No, ensure the gauge has +12 volts and ground. If present gauge is the issue but not likely in your case.
6) Measure resistance between the PINK SEND wire and ground. Depending on the amount of fuel in the tank you should read 33 ohms full tank, 109 ohms 1/2 tank and 240 ohms empty. These are rough numbers since you don't know the exact amount of fuel.
7) If readings are drastically different then the pink wire or the sender is the issue.
You said with the sender removed you measure 33 - 240 ohms which is normal for a good sender. However, when you install the sender are you certain the float arm is not hanging up on the the side of the tank? If you got incorrect resistance readings AFTER installing the sender and tightening the pink wire, you may be turning the threaded sender connection post which can rotate the connection under the sender mounting flange which shorts that connection to the vertical float support which then makes the gauge read full. Again, the picture of this is posted several times on this forum but here it is again. [See a pattern here?
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As a technician you should realize the only way the gauge can read full is if it has +12 volts and ground and the "S" terminal is seeing 33 ohms or less between it and ground. Lastly -- the gauge itself is rarely the issue so that leaves wiring or the sender.
