Need electrical help- no spark., HHHHHHHELP! Options

[tornik550]

I built a /6 2.7 this past winter. I originally ran the engine on a test stand so I could work out all of the bugs. The engine ran great. I had a fairly simple electrical setup and I did not hook up my alternator. Since everything was workin well, I installed the engine in my 914. Once hooked up, I started the car and it ran great for a few minutes than I had to turn it off for unrelated reasons. A week later, I tried to start it up again and everything worked great. Then a couple of days ago, I tried to start the car and after the engine would crank awhile, you could occasionally hear a cylinder fire but the engine never started. Since then, I have not been able to get the engine to start or even any signs of spark.

To check for spark, I hooked up a plug wire to an old spark plug, layer it on the engine, cranked it and looked for spark.

I have a msd blaster 2 coil, pertronix ignition, new distributor cap and rotor, new clewett wires.

Here is what I have tried- none has worked- I tried the above test with each of the listed changes.
-I have tried three different pertronix ignitors (two brand new)
-tried three difference could- Bosch blue, msd blaster 2, accel super stock (none of the three are new- I thought they work ok however?)
-I tried a new set of points (I did get one spark 1 time)
-I have an msd 6al- no luck
-battery has 12.8v

I even tried rewiring everything as though it was on the test stand. Nothing was hooked up to the car- everything was directly to a separate battery
-12v to starter
-switched 12v to starter
-pertronix + wire to + post on coil, - wire to - post
-switched 12v to +post on coil
-ground to -coil post

That is all that was hooked up and still no spark!!! Spark plugs are brand new also. I just don't get it- I have mega simplified the system- everything worked fine and now nothing. I don't even car if the engine doesn't fire- as long as I am getting a spark, I can work from there.

[Whitney Mic]

I even tried rewiring everything as though it was on the test stand. Nothing was hooked up to the car- everything was directly to a separate battery
-12v to starter
-switched 12v to starter
-pertronix + wire to + post on coil, - wire to - post
-switched 12v to +post on coil
-ground to -coil post

That is all that was hooked up and still no spark!!! Spark plugs are brand new also. I just don't get it- I have mega simplified the system- everything worked fine and now nothing. I don't even car if the engine doesn't fire- as long as I am getting a spark, I can work from there.

So after the rewire, you had the coil hooked up as if stock, without the MSD unit, right? This is probably unlikely, but did you make sure the ground was attached to the battery you were using? There would be no path for the returning electrons and therefore no power if the ground was attached to the battery still in the car and the circuit would be in short if the ground isn't hooked to the correct battery.

Time for Volt/Ohm meter tests. Do you have 12 volt power to the coil with the battery in the car? Is there power to the coil from the test bench battery? Power from the coil to the MSD?

I am not a wizard mechanic, but that is where I'd start.

Another thing I would check, because you wouldn't expect to ever have this problem, is to make sure the plugs are gapped correctly...

I had a "friend" in high school that had just tuned up his Austin American. The battery charging system had been giving him problems, so one day while he was at a local mall, he stole a battery from someone's pick-up to make it home. (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/bs.gif)

A few friends got together, and decided that this was wrong, so we showed up to his house in the middle of the night and re-gapped all of his spark plugs to zero on the pavement then put the car back together. At the time, we considered it our own brand of "Instant Carma."

it was a full five or six weeks later when one of the friends involved *finally* suggested that the only troubleshooting step he had missed was the gap on the plugs.

He would never have figured this out on his own, since he'd set the gaps while tuning the car, so he knew they couldn't be wrong. Boy, was he surprised and mystified when he checked those gaps. (IMG:style_emoticons/default/happy11.gif)

If you have friends like that, you should check the plugs.

-- Whit