Suddenly won't start-then it does.

[Red75]

We have been having a problem with our 1975 not starting. Our mechanic has replaced the starter, put on a new battery, traced wires looking for shorts, and I'm sure many other things I've forgotten. It's been in and out of the shop most of the spring. We just drive by and wave at it now and then.

It will start one time, then the next time we try--sometimes an hour later, it won't start. It ran a brand new batter down overnight--twice. He called to tell us it was starting fine-over a period of several days, it never failed to start once. We went to get it, and it wouldn't start.

I won't say he has run out of ideas, but it certainly wouldn't hurt if I could suggest something else to try. (He's ok with that--he's an old car guy-Red is sort of a team effort.)

Any idea what may be causing it? Thanks!

 

[KANE]

We have been having a problem with our 1975 not starting. Our mechanic has replaced the starter, put on a new battery, traced wires looking for shorts, and I'm sure many other things I've forgotten. It's been in and out of the shop most of the spring. We just drive by and wave at it now and then.

It will start one time, then the next time we try--sometimes an hour later, it won't start. It ran a brand new batter down overnight--twice. He called to tell us it was starting fine-over a period of several days, it never failed to start once. We went to get it, and it wouldn't start.

I won't say he has run out of ideas, but it certainly wouldn't hurt if I could suggest something else to try. (He's ok with that--he's an old car guy-Red is sort of a team effort.)

Any idea what may be causing it? Thanks!

Even though the starter was replaced... it still sounds like a bad starter solenoid.

Typically, when the starter suffers from heat soak, it will start and run from a cold start. Then, after it is warm and attempts are made to restart it... it won't start. Usually, the insulation is shot and the starter grounds out.

Four things will kill an electrical system. A bad battery (dead cell), bad alternator (not creating enough output to recharge the system), random short (a bad component, pigtail, ground, etc), or a bad starter (short within the starter).

 

[Red75]

Ok, I may not have been clear--it's been such an long drawn out thing, and I didn't want to write a book here. ;-)

It doesn't seem related to heat--most of the time, it won't start first thing in the morning, and we find that overnight, the battery has been drained. Last week, he tried to move it into the garage for the night, after sitting all day, and it wouldn't start. When he sent someone out to jump it off, it started right up, before he had to jump it. Basically, there is no pattern at all.

I"m leaning toward a short, but he's traced wires until he's cross-eyed.

Thanks though.

 

[KANE]

Ok, I may not have been clear--it's been such an long drawn out thing, and I didn't want to write a book here. ;-)

It doesn't seem related to heat--most of the time, it won't start first thing in the morning, and we find that overnight, the battery has been drained. Last week, he tried to move it into the garage for the night, after sitting all day, and it wouldn't start. When he sent someone out to jump it off, it started right up, before he had to jump it. Basically, there is no pattern at all.

I"m leaning toward a short, but he's traced wires until he's cross-eyed.

Thanks though.

Huh... okay... how about these...

1- Bad contacts on the battery- check them to make sure they aren't the culprit. I've had a bad or loose connection at the terminal that would act funny sometimes.

2- Drain- Pull out the fuse for the interior lights and remove the power to the radio / clock. Then, get a voltmeter and go through the system. You shouldn't lose any current with those ancillary components out of the way. Then go by process of elimination. You'll find the culprit pretty quick that way.

 

[Red75]

I'm thinking he's done the fuse/voltmeter thing, but my record book is in the car, so I can't look it up.

In any case, I'll double check with him to be sure and pass along your ideas.

Thanks!

 

[chevy50]

I had a old chevy truck that was giving me the same grief.So one day I pulled it into the garage with my mind set on finding out what was goin or die tryin!I check all grounds,fuzes,wiring and everything else.I started it up and I took a volt meter and measure the voltage at the alternator,guess what,it wasn't even charging!Someone had change alternators and had wired it up wrong.So not being to smart on this kind of thing,I looked it up on Google and found a picture of how it was supposed to be wired.I switched the wiring around and it started puttin out 14 volts!Also there is a fuzable link at the firewall on c3 vettes under the hood that you can test with a test light,I had one on '77 that ran down 2 die hard batteries before I found it.Turn the switch on and test to both sides of it and see you got power to both ends of it.Sorry about the long response,I hope this helps.Mark

 

[Red75]

Thanks Mark. I'll include this on the list of suggestions for him. I hope it turns out to be something trivial like that!

 

[JohnZ]

Next time you bring it home running and park it in the garage, disconnect the hot lead at the alternator (and insulate the terminal so it can't touch anything grounded), and see if it starts in the morning. If it does, you probably have a shorted diode in the alternator - that can drain the battery overnight.

 

[wishuwerehere82]

It could be the ignition key switch contacts not turning the coil power on.
It seems to me by reading this that it is cranking over, but no ignition sometimes. A bad key switch could crank, but not activate the ignition at the same time.
When it doesn't start, have him check for 12Volts at the coil to determine if the ignition is being switched on.

 

[wallyknoch]

GROUND

It may be as simple as a bad ground. Corrosion between the frame connections causes the charastics you described. The car will seek a ground any where it can. Down to even the emergency brake cables. Many time causing the cables to finally brake. Auto shift cables failures is linked to bad grounds too. I doubt the new parts you purchases are bad, you may have not really needed any of them .