Went to start my car and it totally crapped out. 77 XJC w/350 SBC. Turned the key, car had just been running, starter doesn’t crank and interior lights go out. Silence. New starter, don’t hear the solenoid engage. Don’t hear fuel pump. Slap the voltmeter on the battery just to check, 12.5 volts. I’m guessing it’s a relay. The starting relay on the bulkhead is only 2 summers old. Any idea what the problem is?

 

Dang!!
I *HATE* it when stuff like that happens!!
Check voltage Before relay and After relay with it "activated."
It wouldn't be the first "newish" relay to pack it in way too soon.
I wish you success.
(';')

 

AND,

Check the beast for Start in N instead of P, maybe that safety switch in the T Bar is AWOL.

Meter the battery, 12.5 is borderline, hit start, what you get now?, could be a battery dropping a cell when asked to perform.

 

Just to add and clarify, I have no electric power at all. No interior lights, no response from the starter, no fuel pump..

 

Begin with the basics: battery cables clean and tight, main ground clean and tight (assuming one was installed with the engine swap), cables at the firewall "+" junction posts clean and tight?

Agree with Grant the the 12.5v is on the edge

Cheers
DD

 

Yes, dropping a cell. I have experience with that one.
In my misspent youth once, I was on a Very remote mountain trail, all was well and we were having a Grand Time, until I shut off the key and all was Dead, just as you describe.

No cell coverage, No traffic, NO JUMPERS (which I fixed in about 5 minutes when we got back to town!!) but a forest service pickup sitting nearby, as, unbeknown to us, and just to make things more interesting, there was a Fire in the area!! Fella with me sez, "Not to worry, I have an idea."

I always carried enough tools to do minor overhauls in those days (except jumper cables which I now have in ALL my rigs), so I took them out for him and stood back.

First he took off the ground cable from the battery as battery was dead anyway and extended the hot wire long as possible. That took a bit of time as it had to be extricated from the bowels of the engine compartment (nothing straightforward on that car!).

Then, as the keys were in the Forest Service pickup, he told me to move it over to my car. About that time one of the firefighters appeared from the trees, thought we were up to no good, Of Course, (I wouldn't have believed our story!) and only when he saw provisions already made, and Fella explained what we wanted to do, did he relent and move the pickup into position for us, Bumpers Touching to complete a jumper circuit.

Extended cable reached + post of the other battery, ground was made through touching bumpers and the engine started! Just barely, bit Fella Real good when it did, and was running on the alternator, but it was running at least and we were saved.

THIS was what I wanted! Someone who could think outside the box under pressure, and rub 2 sticks together to make a tow truck!

So I married him.
(';')

 

Lovely story, good for you!

 

^^

Sometimes I think some of the posters here should write a book.

You would be once of those posters LnrB!

PS You need to include a chapter on the Borgward Isabella.

 

As usual, it turns out to be the simplest answer. The battery was installed in 2019. Even though it is a summer only car, and spends winters on a battery tender, still 5 years old. I have voltage but not a deep charge, as it turned out. I had to wait until the weather cleared a bit as it was parked in the driveway when it crapped out with the windows down and I’d covered it. Hooked up the jumper box, fired right off. Even with high beams and AC running, alternator putting out a healthy 13.5 volts. Get the replacement battery, and in the course of installing it find the bolt on the positive side terminal is slightly less than tight, and there’s corrosion under the ring terminal on the ground lead at the battery. Once installed, fires right up.
Of course, a gremlin appears. The turn signal jewels continue to glow after shutting off, and the turn signals will blink with the ignition in Off. Cycling the key makes it stop. Think I need an ignition switch.

 

Well done.

SIMPLE cars these Jags.