65 GTO electrical issues, please help
 

I have my car on a battery tender when being stored. The other day I went to start the car (last time I started the car was January 2020 and it started fine), I flipped on the electric fuel pump and that turned on fine. I left it running for like 15-20 seconds before going to fire up the car. When I turned the ignition key everything went dead, the starter didn't even try, but the fuel pump went off instantly.

Now nothing works at all, no electric pump, no clicking noise by turning the ignition key.

I used a multi-meter to check the battery and it reads 12.9 volts. Tested the multi meter with other batteries (i.e. AA batteries and they measured over 1.5 volts, 9 volt battery measured over 9 volts, so multi-meter seems to be working)

I attached a portable jump starter to the battery and I tried the electric fuel pump and the fuel pump turned on. I didn't try starting the car though. Disconnected the jump starter and again the electric pump would not turn on and battery still measured 12.9 volts.

What do you think the problem might be???

Any help will be very appreciative.

Thanks,
Mark

Assuming you still read 12.9 or so on the battery posts ....

Turn on the headlights.

DId they come on?
...If no, use multimeter to measure from the middle of the + post on the battery to the battery cable attached to the post. Anything more than 0.1 volts indicates a poor connection between the + post and the cable.
................use multimeter to measure from the middle of the - post on the battery to the battery cable attached to the post. Anything more than 0.1 volts indicates a poor connection between the - post and the cable.
...If yes, try to start the engine while watching to see what the headlights do.

Report results.

Check the battery voltage on the Battery clamps , then check on the post, not the clamp that cable attaches to. As described above
you could have a bad clamp connection to the battery post.

What these guys stated is where to start. Bad battery connection most likely. If it's not that, very possibly could be a bad bulkhead connection. The two bulkhead connectors (at the firewall under the master cylinder) can build up corrosion. Simply unplugging them, cleaning the terminals with electrical cleaner or WD-40, and plugging them back in will often fix the issue. When the connectors get too much resistance, nothing will power up. Good luck.

If the above fails, replace the fusible link.

With the battery measuring 12.9 volts when I pull the headlight switch it takes a few seconds before the headlights actually come on. They come on dim but gradually get brighter the longer you wait.

I measured the battery while turning on the headlights and the battery takes a dive down to about 1.5 volts, then the numbers go up slowly until it the voltage reads 12.1 volts. At this point when I turn the ignition on to spin the starter everything goes dead.

I took a reading as stated from positive center post to connected cable and got 0.00. Did the same for negative side and got the same reading 0.00.

I hooked up a battery charger and set the charger to start (55A setting). with this hooked up when I pulled the switch for the lights they came on instantly and full brightness. I turned of the fuel pump and that came on at full pump speed instantly with the headlights still on, tried the ignition switch to turn the starter but just wasn't enough juice to spin the starter (could hear the solenoid click and the starter motor trying to spin but just couldn't spin the motor) the headlights did not dim or the pump slow down during this.

I am thinking the battery is shot, showing proper voltage but for some reason just doesn't have the amps anymore to spin the starter.

The battery is a Deka battery with 1000 CA

The engine specs are in my signature, running about 12.5:1 compression

The starter is a powermaster XS.

Thanks,
Mark

When the "battery dives down to 1.5 volts" where are you measuring? From the centers of the battery posts? From the clamps on the battery end of the cables?

From the center of the batter posts.

Almost surely, your batter terminal connectors need to be removed and cleaned.

I did that prior to all this. Cleaned the battery posts and the cable ends, they are both shiny clean right now, still have the problem. There is no voltage difference from the posts to the cables, center post to center post, cable end to cable end, cable end to battery post, battery post to cable end (measuring + to -)

Thanks,
Mark

That says that the battery itself is not capable of supplying the requested amount of current. Most likely a battery problem. Could be that the requested amount of current is too large (bad starter motor), but I'd definitely start with the battery. All connections are most likely good (or the system couldn't pull so much current).

Battery is what i am thinking. Starter is new just put in last year.

When I get the new battery, I will post if that fixed the issue.

Thanks,
Mark

Yep, try a new battery.

Battery is shot

Thanks for all the help

Mark

The one time I used a brand name Battery Tender on my car when it was in winter storage, in the spring I discovered the thing had boiled the battery dry and I had to replace t. Granted, the vast majority of people who use them don't have any problems, but based on my experience those kinds of chargers can malfunction.

I went back to my old method of simply disconnecting the battery when the car was in storage, and had no more problems. If they are in good condition and fully charged to start with, batteries should be able to sit for six months or more and still be nearly fully charged when you put them back in service.

Yes, it appears the battery is toast. Very easy to exchange with a known good one to troubleshoot.

On any '60's car, there is no drain on the battery when the car is shut off. I have always left my '64 GTO's over winter without a charger and never disconnect the battery. All the wiring is in pristine condition, batteries are about five years old. I simply squirt a little gas in the center carb, turn the key to start each spring. Never had a problem. Why use a trickle charger on an old car?

Contrast that with my 2004 GTO, 2009 G8, 2014 Chev SS---The batteries in these modern cars are constantly drained by theft detection and memory devices for the clock, radio, etc. They need to be on a trickle charger or the battery will be dead in about 4-6 weeks.

Just a little feedback based on my experience.

Thank you guys for that info. I have been using a trickle charger for the last 10 years and this is the only time a battery died on me this way.

I think when I replace the battery this time, I will not use the trickle charger and see how that works.

My car does not get out of the garage a lot or started for that matter that is why I keep the battery on a trickle charge. My car leaves the garage about 3 to 4 time per year and I probably started with out leaving the driveway about 3 to 4 time per year.

Thanks again,
Mark

Is there any way to test the trickle charger to see if it is faulty or not?