Vapor Lock - Part II, I was wrong......
 

Some of you will recall my vapor lock thread from about 3 weeks ago. Car died while warm and then restarted a few hours later after cool down.

At the time, I checked out the ignition system and did not find any obvious culprits. On Saturday night, I was planning on hitting a local cruise spot and experienced the same condition while in my garage with a cold motor......was getting fuel and engine turned but no spark what-so-ever. I rechecked all the connections and after about 3-4 more tries it finally fired. I suspected a faulty tach lead (short) and replaced the terminal. She fired up again, so I buckled in and proceeded to go for a drive.

I was at the bottom of my driveway and she died, again. Just lost all spark! I quickly summoned my neighbors (this is around 8:30pm) and together (with my oldest son steering) we pushed her up the driveway and back into the garage. :(

I followed the MSD ignition tests to the letter, but the results were inconclusive (I'll be the first to admit that electrical stuff is my weakness). I suspect the coil now, but just to be safe I'm sending the MDS 6AL to the factory repair facility today for a diagnostic check. Worse case is I pay a max. of $55 (plus postage both ways) for this service, which to me is cheap insurance for peace of mind. Getting this car flat bed towed is no fun. I also ordered a new coil, cap and rotor from Jeg's this morning to round out the repair.

Yeah, I might be "throwing parts" at the problem, but I feel pretty confident that it's going to go away after this. I also ran a resistance check on the magnetic pickup at the distributor and was showing over 600 ohms, which is within tolerance.

-Deano

Deano,

With electrical problems, there are a few roads to take to troubleshoot it.

Usually, start from the source, or the battery. Check all connections, the ignition switch, ballest resistor (if it has one), fuse block, you get the picture.

If you can't find any intermittent connections, then sending the box back for a look see by MSD may be the answer.

I've seen many poor crimp connections in my time that were very intermittent and drove the owners crazy. Don't be afraid to pull on the wires to see that they are tightly crimped. The best thing to do would be to solder any crimped connections.

Good luck tracing this gremlin ....

- Jim -

Red :

You have mail............

Rick, thanks. I'm sure the module inside the distributor will also get a good going over (if not replaced). A $16 part....I ordered one just in case. I don't mind keeping one on the shelf as a spare.

Jim, since the motor is turning over fine (with each occurence), the battery connections are secure and the ignition switch is right on. Having the fuse block in-between those two tells me that everything there is secure as well. So it has to be related to the actual pieces that produce the spark. At least that's what my logic tells me! :D

But remember, there are many more electrical connections than just the starter motor and battery. Even a tiny ground wire, small diameter, seemingly insignificant, can cause the engine to stop running (particularly if the ground wire is something associated with the distributor)!

I had a problem just like that, It turn out to be the roll pin that hold the cam drive gear to the distributor:CRY: it would catch in the right spot to run then a week later it would slip and die. Took about a month to find the problem:JEKYLHYDE
Mike

I'm having difficulty understanding this particular condition as a "variable" situation. It would seem to me that either the roll pin is firmly holding the camdrive gear to the distributor shaft, or it's not. :confused:

It would free spin sometimes (then the motor would die)and for some reason it would catch in the right spot and run. it was just dumb luck that I found the roll pin was sheared. hope this helps. Mike

Mike, I'll pull the distributor as a LAST RESORT if $150 in parts and diagnostics doesn't cure it. I'm taking a neutron bomb approach toward resolution....kill (eliminate) all of the ignition components but leave the engine intact. :D

You might try grabbing the rotor with it in the motor and see if it will spin, it's worth a try. Mike