No Start after leaving key in on position for 30 min
 

I was working on my power window regulator and left the key in the on position for maybe 30 minutes. Now the car will not start. It just turns over. I swapped the red relay for another (good one). That didn't help.

Is it possible to burn something out by leaving the key on?

Car is a 1981 911SC. All stock CIS.

Thanks!

Can you hear your fuel pump running when in the on position without turning it over?

Battery drained below minimum voltage. Jumper it or push start and drive her around for an hour

Check voltage I bet it is below 12.5

Put it on the charger and walk away. Don't get spooked.

Yep you drained the battery. :).

It's not a dead battery lads.

"1981 SC"... Check the fuel pump relay. I'd bet you bumped it when you were working on the electrics at the fuse box for your power windows. (Reiver is on the right track)

OP states it turns over- if starter turns, the battery can't be drained down too much.

Pull the relay and crank it over several times then reinstall the relay and it should start right up.

That didn't work. What would be the point of pulling the relay?

It's not a dead battery. Battery was 12.2v. Car turns over fine. I gave it a little charge anyway which didn't change anything.

I was working in the passenger side door. The window regulator and motor now work perfectly.

So, is there anything common that can burn out by leaving the car in the on position. If no, I will start basic troubleshooting (fuel, spark, etc).

Thanks

Did you smell fuel when cranking?

If not, then pump may be out.

Also, 12.2v is not good enough, try charging for a little more or jump it.

Spark.
 

I don't think It's the coil, but, check for spark by
pulling #1 & grounding to the engine.

How old is the battery?

Also, check the battery voltage while cranking the engine.

Gerry

Chances are you burned up your coil.

Burned coil, stuck/burned points, bad CDI.

You need a minimum of 12.5, once you know your battery is ok, proceed to other items if it still won't start.

I ruled out the battery. I did put the charger on the battery last night and topped it up. It still doesn't start.

Can you hear the fuel pump running?
If it has points, put a new set in.
Are you getting spark?

'81, no points.
Green wire to dizzy in good shape?
Get your battery voltage up first as others have said.

OP, any unburnt fuel out of tail pipe?

A little different look at this, but do your interior lights work when you open the door? I ask because you were working inside the door and the CIS lambda oxygen sensor/fuel frequency valve system operate on the same circuit as the interior door lights/door switches in the inner door sill. A non functioning lambda system will make car hard or fail to start. Maybe you accidentally disconnected or shorted the interior light switch and need to just check your fuses? Good luck, Tim

Is the cis/lamda the box under the passenger seat?

Battery is good. I hear the fuel pump run.

Unfortunately I haven't had more time to work on it today.

Yes the lambda box and its relay are under passenger front seat. Tim

A battery that measure 12.5 Volts is at 80% state of charge, 12.2 is 50%

See if there is a spark. The CDI might not have liked having a high voltage on it for so long.

The only useful troubleshooting info of the thread!

I was told I would burn up the CDI if I left the key on that long.

You need fuel and spark for the engine to start. Let's hear from the OP whether he tested for spark (ground a spare plug to the engine and crank) and missing fuel (introduce starter fluid into the intake).

FYI, a coil doesn't burn up with the ignition on and the CDI box should not be affected by that either unless it was on its way out to begin with.

Ingo

Marginal CDI capacitors have been known to fail under that condition.

Same happened to me when I left the ignition on in my 82 while working on my radio. Flooded my engine but finally got it fired up with lots of cranking and pedal floored (clear flood mode).

Spark test.
 

I really wish he would look for that hot blue spark...........

Gerry

I'm not the one who figured it was flooded but it was the tech/owner of the stereo shop who does a lot of installs on 911s, said it was a common problem on 911s when ignition is on for extended periods. He was right!

I will check this week. I ran out of time on the weekend.

I hope it really is just flooded. That would be great.

I'm getting a little frustrated with old cars. I was just getting my 911 into good shape. I spend a month last summer diagnosing a lose wire in the fuse box that created an intermittent starting issue. I conquered the power window motor on the passenger side and figured out how to tighten up the flag mirrors without completely taking them apart. The car was running and starting better than ever. And then, no start. :mad: A 30K mile Cayman in mint condition is looking like a good option right now.


-Anthony

Before anymore testing, unplug your fuel pump relay.

My hunch is CDI box.

I tested. There is no spark.

I put the ohm meter on the coil and it checks out.

I was reading about CDI symptoms and during my last drive I was getting an erratic tach around 3k rpms.

Next you need to verify:
1. The CDI has 12 volts.
2 The CDI has a signal from the distributor (possible bad green wire).

The CDI does whine. That means it is getting power, right? How can I test for sure? Test for 12v at the plug?

How can I test the green wire?

Yes, it's getting power. Use an ohmmeter to measure between 7 & 31 (opposite one another) on the connector
and check for 600 ohms. Then measure for about .5 - 1.0 volts A/C while cranking on those pins.
Then check for continuity from the CDI connector to the coil and verify a good ground
on the coil. If all checks are OK, then the CDI unit is bad.

If the CDI is bad, you can send it to Pelican Parts for rebuilding.

How valid are these tests (first post):

http://forums.pelicanparts.com/porsche-911-technical-forum/649722-how-test-6-pin-cdi.html

When I do them I get:

pins 1-3 flickers between .1 and .3 ohms
pins 1-4 2250 ohms
pins 2-5 1.3 ohms
pins 1-5 my Fluke doesn't measure capacitance

Same issue here.

The coil had overheated.

A new one and all works fine.

To really test the box make 3 small extension wires about a couple of inches long: spades on one side and spade sockets on the other side. Then make two longer wires with spade sockets and leave the other ends open. Connect the CDI box to pin1 (GND) and pin5 (power) and pin4(coil) with the short extensions to the harness connector. Then use the two long wires and connect them to pin3 (GND) and pin4 (signal) of the box.

Use a High-Tension cable and connect it to the center of the coil and the other end to a spare plug that is grounded to the engine body. That's your test setup. Get an AA or AAA battery. Turn the ignition on. The box now should whine.

Touch the wire coming from pin3 to the positive terminal of the AAA battery and the wire coming from pin4 (signal) to the negative wire of the AAA battery. Every time you do this the box should release a spark. If you reverse the connection nothing will happen.

Ingo

Do you have a Pertronix? I just read a thing today about leaving the key on and the Pertronix will burn out the coil.

Pertronix says, in their FAQ section...
What will happen if I leave the ignition switch on when the engine is not running?

Leaving the ignition switch on when the engine is not running, can cause permanent damage to the ignition system, and related components. This does not apply to the accessory position of the ignition switch.