My apologies in advance if this is a dumb question. I'm trying to diagnose a no start condition on my '69 Cutlass S with original 350 2bbl. The car has its original point distributor with an aftermarket coil. My question is - how would a bad chassis ground manifest itself in the starting circuit? Additional information:
I've checked my battery, starter, coil connections, etc. Everything is in order and the car has been starting fine almost every day. With the key in the on position, I have power on the + and - side of the coil. I have no spark at the plugs. There are three potential failure modes at the distributor;
1) Coil wire to the cap - I've checked this and the connection on both ends is good. Coil checks out OK.
2) Negative coil wire to the points - I have not checked continuity on this wire (I will) but no reason to think it would lose continuity all of a sudden.
3) Ground wire on the breaker plate - this could be suspicious due to fatigue in the original wire. I'm not sure how to check it without removing the distributor and just pushing/pulling it to check.
If I had a bad chassis ground, would I have power coming out of the coil and going into the distributor but none coming out of the distributor? Or, does this mean the problem is in the distributor?
Thanks in advance for any help.

 

This wouldn't be a chassis ground issue. The main ground goes to the engine so everything engine wise grounded. Chassis ground issues would be inop lights, interior options etc. Put a test light across the coil and see if it flashes while cranking. That will get you moving in the right direction.

 

How about backing up and defining "no start". The engine cranks but you have no spark? Power on the positive side of the coil is a given. The negative side should alternate between 12v when the points are open and 0v when the points are closed. If the negative side of the coil is always at 12V, the points are not closing or they are burned or the wire from the coil to the points is open or the ground wire from the point plate to the distributor body is open. Do you get a proper dwell reading when cranking the engine?

 

I had a similar problem three years ago with my '69 4-4-2 where it would crank but not start. It boiled down to a faulty condenser in the distributor. Once changed out for a new condenser, it started right up and hasn't given me a problem since.

Randy C.

 

The only way a condenser failure could cause a no-start symptom is if it shorted, but if it did that he would be measuring 0 Volts on one side of the coil. So that is highly unlikely in this case.

Based on your symptoms, either your points are bad / not closing when cranking, or you have an open wire between the coil >> distributor >> points >> ground.

 

This^^^^^^^^^. I've found with a bad condenser, you usually get a lot of back firing where the engine tries to start and kind of acts like the distributor is 180* out or it runs like crap with a lot of backfiring.

 

^^^This, which is why I wrote what I did.

 

Sorry for any confusion. Let me attempt to clarify.
Yes, the engine cranks but there is no spark at the cylinders. I did not check the negative side of the coil while attempting to start the engine so I will need to do that to confirm whether the voltage there is constant or switching from 12V to 0V.
I was incorrect in asking about a bad 'chassis' ground. I suppose I meant engine ground. Back in the '80's when I was a dumb high school kid I put a tach in my '72 Chevelle. I chose a poor location for the ground and learned real quick that the engine would turn over but the car wouldn't start. I had no real diagnostic skills at the time but it was obvious that something in my tach wiring caused the problem so I disconnected everything, car started, and I figured out what I did wrong. So this question doesn't necessarily have anything to do with my current problem, I'm just curious. In a situation like that there is still power going through the starter to turn the engine over but no spark was getting to the cylinders. Where would the breakdown reveal itself?

 

Let us know what happens when you check the voltage on the negative side of the coil while cranking.

 

Time to provide an update here and close the loop on this one. Long story short, it was the points. The wire and electrical checks at the coil and breaker plate all checked out. I also changed the condenser. Everything I've read and heard is the new condensers are crap. However, I don't know the age of the one that was on the car so I changed it out with a new one from NAPA. I kept the old one just in case.
Thanks again for the responses and help on this. I switched my 442 over to a Pertronix in the late '90's (never game me any problems for 20+ years) so this is really my first experience with points.

 

Most people don't realize that a points system is probably the easiest to troubleshoot.