Yet another fuel gauge issue...solved!

[leddzepp]

The fuel gauge in my 68 worked up until recently...then it suddenly "froze" at 1/2 tank. I unplugged the sending unit wire at the fuse panel...nothing. I tapped the gauge cluster, wiggled the plug, still nothing. I create my own sending unit wire and ground it...nothing. There is power to all other gauges so I assume there is power to the fuel gauge (in hindsight, at this point there was not). I assume it's a gauge problem, so I remove the gauge and rig up some wiring and connect it up to a car battery, and it zero's out (works). I then pull the sending unit and wire it into the gauge setup I created, and move the float arm...the gauge responds accordingly (it also works). I reinstall everything and the gauge pegs out, past full at 3oclock. Once again, I attach a ground at the fuse panel and the gauge stays pegged. Now I'm CERTAIN I have power and there must be a break in the sending unit circuit between the gauge and the fuse panel. I'm "guessing" a crack in the circuit board, or less likely a break in the wiring from the plug to the fuse panel. I inspected the board with a small dentist mirror, and the plug (I never removed the entire cluster) and all looked well. Just for grins, I decided to use a small jewelers screwdriver to "bend back" the number 4 prong (sending unit wire) pictured below, to make sure it had contact with the circuit board when plugged in. PROBLEM SOLVED!! I also went back and did the same thing to number 3 prong (power wire) to ensure the gauge does not lose power and freeze again. In the end it ended up being a double whammy

Just thought I would share this, as every thread and FAQ I searched on the subject mentioned a faulty sending unit wire, faulty gauge/resistor, faulty sending unit. Hope this helps someone else that can't get their fuel gauge problem diagnosed before buying new parts that aren't necessary.

[leftybass209]

Awesome! Glad to hear you figured it out. Should benefit many people down the line.

[midniteblues]

It's a hard lesson to learn too make Full contact on any connection.

I just did the same thing kinda installing a hei wire into the bulkhead. It wasn't entirely seated/ clipped in. An when I bolted the bulkhead back in it pushed the spade out...
Athough I kinda figured it out quickly with the test light at the distributer.

Most times I like to fluff the cluster pins but it reaks havok on the circuit board. It's when you don't that you end up scratching your head.

I don't believe anyone would have suggested it though.

[VetteVet]

Congratulations on finding the solution and thanks for posting the cure. Very few guys ever give feedback to benefit the rest of us.

Those of us who know the wiring and electrics on these old trucks can suggest what the problem is and what may be causing it, but it is really up to the individual to follow through with the troubleshooting. VV

[toolboxchev]

Thanks LeddZepp, I currently have some issues with the gauge and I will focus on that first thing.

Thats awesome!