Please help me diagnose a starting issue/drain/batt going dead...

1955 Chevy pickup, '59 Cadillac 390, generator (rebuilt last year), starter rebuilt last year, new repop factory style wiring harness (no fuse box like stock), new voltage regulator, new horn relay (no other relays), new battery within the last six months.

The issue is the truck is not starting once in a while. I get 13.8 volts at the battery while it is running (same or close on the generator while running), no drop when ignition is shut off. It might start fine seven times running around town for three days, then out of nowhere no starting and sounds like the battery is dead.

I haven't checked the voltage at the battery after sitting a bit, as I just started driving it again after it sat for two months while I had my doors off repairing rust in the bottoms. It had this same issue a couple of times before. I thought I had fixed it when I found an issue in the voltage regulator and replaced it. Then I found an issue in the horn relay and its batt wire connection so I replaced that and fixed the wire. It fired right up after sitting two months without running. Three days later, driving around town, dead battery sypmtoms. It will jump off just fine and seems to charge.

The fact that it sat for two months and started up fine leads me to believe there is no drain. The fact that it seems to be charging leads me to believe it is not a generator issue. Maybe a starter solenoid?

I have a volt meter and a teeny bit of electrical knowledge, just enough to get me in trouble, lol. Help me figure this one out. Pretty please. Thanks!

 

take off the ground cable from the battery and place a test light between it and the battery. if it glows bright you have a draw, remove one fuse at a time and see what happens

 

I don't have a fuse box, the truck didn't have one from the factory and my replacement stock style harness doesn't have one either. Besides the starting/charging circuit, I have lights and a radio.

I'll go check with the test light. But it wouldn't seem to have a draw if it sat for two months and then started right up. I'll report results from the test light...

 

then disconnect one circuit at a time and see if the light goes out

 

Light comes on with negative batt cable disconnected. Would the radio clock/memory function cause the light to come on (tiny draw?)? Or should I keep looking?

 

This sounds like a common GM problem. Starter solenoids on GM take a FULL 12 volts to fire the starter whereas a Ford takes about 8 volts to pull in. It is up to you but, I would put a Ford solenoid on it and put a jumper wire on the GM solenoid from the main cable to the start terminal. Use the starter wire to fire the Ford sol. and I bet it fixes it!

 

have you checked your grounds? I had a problem like that with a van years ago and it was a loose greasy ground on the engine. Mike

 

If it only does this when its hot, I'd bet turbox2 has your fix.

 

You spent US American dollars on that sweet truck, and DIDN'T buy a harness with Fuses??? Hope you bought a Fire Extinguisher....Praying for ya son....or your truck....

 

Mike, the grounds all seem to be good.

 

Lol, it didn't have a fuse box from the factory and I don't recall any stories of a half a million trucks burning to the ground when new. I don't have any fancy electronics, just a radio. The factory headlight switch has a mini glass fuse in it and breaker contacts.

 

It seems to happen hot or cold. Sometimes when cold or hot, very slow starting. Sometimes when hot or cold just a couple of turns then nothing.

 

I have been charging battery on my car all winter, not used often trying to sell it.
Went to start it again today,dead I,m going to buy a New Battery.

 

are you sure it is charging? you said "I get 13.8 volts at the battery while it is running (same or close on the generator while running), no drop when ignition is shut off." normally the voltage is higher on the battery when the engine is running (generator is charging) and drops to just the battery voltage when the engine is shut off. The fact that you get the same voltage on the battery engine running or not doesn't seem right. How do you know the generator is charging the battery when the engine is running?

 

Well your starter gets its juice thru the big cable.
That starts at the battery - check connection at post and cable to clamp condition. The cable can corrode inside the insulation

Next it goes to the solenoid - check those connections there
Next it goes THRU the solenoid and that's internal there . There's some parts in there than can get goofy and cause current flow problems.

That solenoid needs 12 volts from the ignition switch - and a solid 12 volts . Could be in the switch and or the wire headed to the solenoid

The other side is the grounds and the same corrosion can happen there .

It will be a simple fix but tricky to find

 

Could be a bad solinoid ,contact disk inside with a bad/burned spot not making good contact sometimes.

 

If your test light stays on when it's hooked up between your negative cable and the battery post, you have a parasitic draw on the battery. You will have to start unplugging componets to find the draw since you don't have fuses to pull. You might want to get your battery tested also.

 

I'm gonna vote solenoid also.
I've seen them get weak over time, and I've seen weak ones fresh outta the box (usually cheap white box parts).
They'll start fine most of the time, but every so often 'click' and nothing else.

 

Mr. T, if your truck is like mine, the ground from the battery goes directly to the firewall. Then there is a cable from the body to the frame down below that. They both need to be there for the starter to spin. Adding a Ford solenoid like TurboX2 said seems to help a lot of Chebies, but I've never tried it.

 

I only assume the generator is charging because of the voltage reading at the battery. Generator was rebuilt and bench tested by a pro a year ago.

I have physically inspected wiring between battery and starter, and starter and generator, and from starter to key swtich. Connections are good. All wiring is new, about a year old.

The battery is about six months old (a good one), and was tested good shortly after purchase because of the same problem.

My battery is now in the bed in a batt box. There is a ground to the frame from the batt. The cab is grounded to the frame. The engine is grounded to the cab and the frame.

 

Despite all the ground points between frame and body, I'd put one from the battery to the engine block.

As it's intermittent, I'd probably blame the solenoid, it's got moving parts that can fail.

 

It appears you have a parasitic draw while off, I would start with the generator, and then the radio. The regulator has a shut off relay that may stick closed, and I have seen newer radios start to draw large currents from the clock circuit.

 

I disconnected generator wiring and the test light still lit up.

 

How's the ignition switch ?
Remember "new" doesn't mean "good" - sad but true.

Sometimes the gen/alt can have a bad spot on 360*s. if your lucky enough to stop on the bad spot you'll experience intermittent problems. It's a bit obscure but I've seen it more than once.

I see you've eliminated that while I posted

 

If the radio has an LED display or memory, it's on all the time. If easy disconnect radio power and see if the test light goes out.

 

What gauge cables? Positive and negative?

 

First see if you have a drain take a light bulb,or AMP meter,try high scale you have30amps.
Remove Neg terminal put meter or bulb in between and see if light goes on.
Also if you have battery terminals that sandwitch cable,2 bolts.
Clean and may have to cut 1/2off if bad.

 

That's next on the circuit list to check, although I assume it will draw power when the ignition is off due to the display/memory and I that shouldn't be enough to drain a battery. But at least I'll know if the light goes out I don't have any other drains. Besides the radio, what else can cause a parasitic draw? I assume a frayed wire somewhere grounding to metal can? I only have stock lights and stock gauges, no led's or halogen bulbs, and the lights do not stay on when the truck is off, lol.

Also, with regards to the keyswitch 31vicky asked about, it's a new repop.



I also went ahead and go a new starter solenoid so I would have it on hand just in case. That wasn't replaced when the starter was rebuilt because it tested good. It's pretty much the last thing on the truck that is not new.

 

Is the battery actually dead, or does it just not crank? The answer to this question will help to determine where to go from here. I am also wondering what type of ground between the battery and the block. It has to carry just as much current as the positive battery cable.

 

Terd, I would run a #2 cable from the battery ground terminal to a clean spot on the block near the starter. I also use star washers between the cable terminals and the point where I terminate the cable, better bite into the metal.
Hope this helps KK