Starting Issues, Please Help!

[gwarvo]

Okay Pelican, I need help and suggestions! The car is a 1970 911T with a 3.0 SC engine and weber 40 carbs. The ignition system is upgraded to the MSD 6AL.

I went out to start the car back in late December and it wouldn't start. Car had been running and starting fine on the last drive I took it on, probably mid to late November. I first suspected a rotor cap. Replaced that and nothing. Next thing I replaced was the coil because it was an older Bosch coil and I had read those are common to go. I bought a MSD Blaster 2 coil. That didn't fix the issue. I just pulled a spark plug so I could test if it was getting a spark and it was wet with fuel. I knew this wasn't a good sign but tried anyway and confirmed no spark. I hooked the volt meter to the tabs on my coil to see if it was getting power and it was very sporadic. The only thing I can think now is it's the MSD itself. It's an older model probably from early 2000's when the engine was rebuilt. Would you say that's the next thing in line or any other suggestions?

Thanks in advance for the input and help!

[timmy2]

Check both power supplies to the MSD?
(Switched and constant)

[gwarvo]

Originally Posted by timmy2

Check both power supplies to the MSD?
(Switched and constant)

Thank you for the quick reply! I was poking around to see if there was an easy way to do this and after looking at videos online, it seems like it is getting power. So I'm guessing it is the MSD that is bad?

Also would a bad voltage regulator or alternator be the cause of this going out?

[Walter_Middie]

You will not see any voltage at the coil as it only gets a pulse from the CDI (MSD box).
It could be the CDI, but you can test that.
Does your distributor have points? Is your distributor from the 3.0 or the original 2.2?

To get a spark to the spark plug in the engine:
First, you need power to the CDI.
Next you need to have a way to trigger the CDI
Then the CDI will send a pulse to the coil which will increase the voltage and send it through the high tension lead to the rotor and to the selected spark plug. You need to verify that each step in this chain is working. 



1) Verify that the CDI is getting power. You've already done this.

2) Verify that the CDI is producing a spark. You can do this with a "telegraph" test. Take the high tension lead off of the center of the distributor and put a spark plug on it. Ground the threaded part of the spark plug. With your plug attached to the center lead, open the distributor, remove the rotor, place your key in the run position, and manually open and close the points. Each time you cycle the points, you should see a spark from the plug. If you do not, you may have a bad CDI.



3) Verify that the coil gets a signal when you crank. Replace the rotor and distributor cap. Leave the plug on the center high tension lead. Crank the engine. Do you see a spark? If so, you are getting spark to the distributor. If not, your point gap may be off or there is some other problem with the connections. 



4) Verify that the spark goes to the spark plug wires. Reattach the center lead to the distributor. Attach your spark plug to one of the leads going to the cylinder spark plugs and ground. Crank engine. If you see a spark you may have a timing problem. If no spark, you have a problem with your rotor or distributor cap or your wires are improperly seated. 


[WMontald]

I had the same issue after long standstill.
Thought my CDI unit was the problem.
But it where he breaker points that did not open.
Removed the distributor cap on my Marelli and opened the breaker points with a screwdriver.
Filed them with Breaker point file.
Spark was back.

[timmy2]

Likely no points in the SC distributor.
Just a reluctor. Need to crank the engine using the starter to see if it is firing in the same method as Walt described. (Except the points)
The green wire to the distributor can fail, usually right where it comes out of the distributor.