Won't start! I need some debugging assistance

[BoogieOnSkis]

Strange -- I got in my car this morning and it didn't start. It was running perfect last night without any indications of problems. It's an '82 911SC.

The engine turns over (nice and strong). But, it's either getting no spark or no gas.

I opened the air box and with the ignition on, I lifted the switch and heard a buz. I assume that means it's getting fuel.

I removed the fuse cover in the engine compartment and found that the 25A heater fuse was blown. Replaced it and swapped a few of the relays including a couple up front. The rest of the fuses (included the ones up front) looked good. Unfortunately it still does not start.

This evening I plan to get ahold of a timimg light and check for spark.

Can anyone suggest anything else I should look at? By the way, I replaced my coil about a year and a half ago. I inspected it this morning and it looked good (no black ooze).

I appreciate any assistance -- Thanks!!

[Superman]

You're headed in the right direction. the buzzing you heard should have included the fuel pump, but it should also have included a...well a....sort of.....squeal. That is, the injectors themselves make a shine or squeal noise when they spray. Regardless, if you are getting fuel but not spark, then trying to start your car will result in a garage that smells like gasoline. Unmistakable.

With an assistant and no timing light you can pull the high-voltage lead from the center of the distributor cap, hold in near a metal object and have the assistant try to start the car. A blue spark should jump at least a half-inch, making a SNAP sound at the same time. I STRONGLY recommend you use well-insulated pliers to hold this wire for the test.

[makaio]

Originally posted by Superman
I STRONGLY recommend you use well-insulated pliers to hold this wire for the test.

I second Superdudes advice! Or don't hold it at all.

I had a similar experience once with my SC. Ended up being my battery. I'm not suggesting that is your problem, but just a possibility. It had something to do with my battery wasn't producing enough juice for the system.

[emcon5]

Do you have a Bosch CDI or a Permatune?

The Bosch should have an audible whine if it is working.

Tom

[stlrj]

Was the car parked outside overnight?

Joe

[na2ub]

Same symptoms for me. Turned out to be distributor cap & rotor. It would turn over and over and every once in a while give a splutter, but that's it. Didn't really smell that much like gas, but it was outside.

[BoogieOnSkis]

Thanks for the responses!

I have a Bosch CDI (no aftermarket stuff). But the coil isn't Bosch. At the time I replaced it, everyone was backodered for the Bosch coil and no one knew if Bosch was going to continue making them.

The car is always garaged, but it's a daily driver.

I thought the whine comes from the CDI. I don't remember hearing a sound from the injectors when I lifted the switch; and there was no strong gasoline smell.

The fuel filter is on my list for replacement. Could it have clogged so suddenly?

I didn't check my cap and rotor this morning. But I replaced them about 15K miles ago.

[Zeke]

I can't hear a whine from my CD box and I'm having some major trouble. (See thread *bad miss*). My fuel pump is located directly below and makes a pretty good whine of it's own. So, I don't know how to tell the difference. I guess I could pull the fuse to the pump and listen. Do you hear it with just the ignition on? Will these things work partially before dying completely?

[emcon5]

Originally posted by BoogieOnSkis
I have a Bosch CDI (no aftermarket stuff). But the coil isn't Bosch. At the time I replaced it, everyone was backodered for the Bosch coil and no one knew if Bosch was going to continue making them.

What coil do you have?

Tom

[cantdrv55]

Hey Bob,

Welcome to the club. I've been tshooting my no-start problem on my targa for a few days now. When I disconnected the fuel line to injector #4 and lifted the switch in the air box, I got no squirt or drip when I try to crank the engine. I also don't hear anything from my fuel pump but then again, my coupe starts up fine and it's fuel pump doesn't seem to make a noise either. Let me know what finally fixes your problem.

[BoogieOnSkis]

Alright. I have an update.

I attached a timing light and it's not lighting up at all when I turn the engine over.

I've done a little probing around and I'm not seeing any voltage on the positive terminal of the coil when the ignition is on. This really sounds like a blown fuse, but all my fuses look good.

Which fuse (or fuses) are on the circuit that leads to the positive on the coil? Is there a relay involved?

Tom, the label has fallen off my coil, but it's colored blue and has another label that says "Quality inspected by KEM Manufacturing". I think it's just the OEM replacement coil.

Thanks!

[cab83_750]

Originally posted by makaio
I second Superdudes advice! Or don't hold it at all.

I had a similar experience once with my SC. Ended up being my battery. I'm not suggesting that is your problem, but just a possibility. It had something to do with my battery wasn't producing enough juice for the system.

Ok, I need to add this skill to my list. I have known and heard about this, but:

1. Pull out the wire from the center of the distributor.
2. Using non-conductive pliers, hold it .5 inch away from a metal object.
3. Try starting the car. An arc should become visible.

Question:
In #2, is there a 'safe' spot to point the coil wire (fan housing strap? engine mount bolt?) Will this not mess up electronics?

[emcon5]

I hope this isnt the case, but.......

Originally posted by Early_S_Man in another thread

The Bosch Blue Coil is MOST ASSUREDLY NOT the correct coil to be using with a Bosch CDI unit!!! Using that coil can destroy the CDI unit if/when the coil shorts out internally!

The two most common Bosch part numbers for the correct CDI 'Ignition Transformer' [factory speak for coil] are 0.221.121.001 and 0.221.121.006 ... former is the '70 - '73 part with '1', ''4', and 'A' terminals, and the latter is an SC coil with 'A', 'B', and '4' terminals ... with the 'A' and 'B' primary terminals offset on one side about 1" apart.

From here:
CDI thingy failed / Options?

[BoogieOnSkis]

Thanks, Tom. But, I'm absolutely positive it's not Bosch -- It's probably KEM (I believe they manufacture coils).

[BoogieOnSkis]

Update -- Good news!!

I was following the troubleshooting instructions in the Bentley manual this morning; I disconnected the CDI box connector and confirmed that I had battery voltage on pin 15 of the connector. I plugged the connector back into the CDI box and my car started right up. My connector must have been loose.

Thanks again for everyones help!

[Rot 911]

Never hurts to start with the easiest and cheapest! Now get back to driving.