Charging System Troubleshooting--Blown Ignition Light Fuse?

[patrickt]

Originally Posted by ACHiPo

My fuel gauge has been flaky for a couple weeks. I suspect a bad fuel sender. I was planning to troubleshoot this weekend, but resolving the charging issue took priority.

Yep, that's a clue. Let's see if we can get lucky -- reach up under the dash to the two green wires going to the spade terminal on the fuel gauge. Pull those two green wires off the spade terminal and don't let them touch anything. Then put a fresh fuse back in fuse #3 and then fire the car up and see if everything, except the fuel gauge, now works properly and charges properly.

[ACHiPo]

Originally Posted by patrickt

Yep, that's a clue. Let's see if we can get lucky -- reach up under the dash to the two green wires going to the spade terminal on the fuel gauge. Pull those two green wires off the spade terminal and don't let them touch anything. Then put a fresh fuse back in fuse #3 and then fire the car up and see if everything, except the fuel gauge, now works properly and charges properly.

Will do that right after coffee (and reinstalling the alternator and voltage regulator ). I'm a hazard to myself and others before caffeine.

Edit: ok one cup down, and my head is clearing. If I pull both green wires from the fuel gauge it eliminates the fuel sender from the circuit, and also the wiper switch and motor. It also seems that if there is a short to ground through the fuel gauge circuit there should be low resistance from the fuel gauge green wires to ground? I think I'll try that test first.

[patrickt]

Here's a pic of the green wires on the back of the fuel gauge that I want you to pull off the spade terminal. This is a pic I took of when I wired in a 10v Smiths regulated voltage supply which I found made the accuracy of my fuel gauge better. That's what I'm holding in my hand. Anyway, the fault is either on that green feed wire that goes from the ignition light, to the fuel gauge, to the tach, and on from there OR the fault is on the other side, which is the voltage regulator. Either way, it should be easy to trace.