Electrical help needed AGAIN

last year I went though the electrical system rebuilding the alternator, etc and all was good.

Today I go to start the car. Fuel pumps ran, I press clutch and brake preparing to start engine and all power goes away. I press clutch and brake a couple more times and power returns for about 3 seconds and then dies again, never to return.

Battery is one week old and checks out at 12v.
Fuses in engine bay are not blown and power there measure 6.7 volts
Power entering fuse boards up front at spare tire measures 12v
Power at voltage regulator measures 6.7 volts. Swapped regulator with a modern regulator which I have but have not installed and there was no change.

Jiggled various wires with ignition switch on and got no response

I’m very much an electrical rookie.
Any insight greatly appreciated.

Car has no electrical power at all and is totally dead,

 

I’m a bit of an electrical rookie as well but the first thing I would do is make sure your battery has really good +- connections and I would really check the battery ground and make sure it has a great connection. Do you have a battery shutoff switch? The ones mounted to the batteries with the rotary knob often go bad.

Freeman

 

Thanks Freeman. No shut off switch. Last fall I had a cracked positive terminal connection which gave a similar result. At the time I thought as long as the connections were touching the battery you would have power. Not so. The connections must be super tight which they now are. The fact that the wires entering the fuse board are showing 12volts should mean the connections are good at the battery. Any other ideas ?

 

Might be the engine earth strap. Try connecting a single jump lead from the chassis to the engine block (anywhere metal on the engine) to make sure the engine has a good earth and try starting it again.

 

My money’s on it is a bad ground!

 

Does that mean like a jumper cable. If not, can you give me an example ?

 

I connected a alligator clip to the engine and touched the bare wire end to the chassis and had no results. Any other grounds or things to try ?

Appreciate the input.

Skipp

 

Even though the battery shows 12V, maybe try jump starting it? Maybe a faulty battery? You mentioned you replaced the battery a week ago.

 

Image Unavailable, Please Login You guys were 100% correct.

Problem solved. Thanks for the help guys !

After jacking up the car and finding nothing amiss, I went back to the battery terminals.
Using a multimeter, I took readings at various spots on the battery cables and found that I wasn’t getting 12v on the ground cable connectors and bare wire consistently.

I got a set of jumper cables thinking I’d try grounding the negative side if the battery to something else. As I connected the jumper cable to the negative battery terminal, I got POWER ! But not for the reason I was thinking. As I wiggles the jumper cable clamp a bit, the edge of the clamp would touch the metal nut used to crimp the bare wire to the negative connector. I’m on to something !

The two bolts that sandwich the bare wire to the terminal connector were way loose.
I had a Battery Tender go bad last week and I replaced the battery as part of that saga and must have giggled the loose battery wire just enough to make the contact fail.

It was very exciting to see the car spring to life when I made the proper ground!

FYI, don’t drop a jumper cable clamp on your big toe.