It's a Delco points distributor, I have spark at the coil but not out of the distributor. The coil gets 12 volts in "run" and "start". I changed the condenser but there was no change. I changed the rotor, also no change. The points are free of corrosion and gaped to .019". There is continuity between the ground wire and the body of the distributor. I don't know what to check next, please help! Thanks.
When diagnosing a system, I've found it helpful to sometimes step back, break the system into sub-systems, and move from the end to the beginning. Example: check spark by pulling plug, grounding to block/head/whatever, and install wire. Spark good, weak, or AWOL? Spark weak/missing, ditch the plug and try from the wire itself. (this step is more likely to come in handy for a single-cylinder misfire). Still no dice? Jump to the coil wire. Good/weak/missing spark? Good spark here means the problem is in the cap/rotor or wires. I say pitch 'em both if they're not good quality and recent. Bad/no spark could be coil or primary ignition. A quick and dirty is to pull the wires off the coil, run a hot wire to the + side, attatch a wire to the - side, hold the high-tension coil wire near a grounded surface, and have a helper tap the wire from the - side of the coil to ground. This gives a make-&-break circuit whch will trigger the coil and cause spark. If the coil is good, and if the coil wire is good. But if the test comes negative, you can always try stealing a plug wire for testing purposes; liklihood of it being bad too isn't very great. A volt meter will tell you how much voltage you have going to the coil, how much your ballast resistor (if you use one) is dropping the voltage, and if the voltage is actually making it to the points. You could have a bad connection or short in the primary circuit inside the distributor (rare but possible). A trick I use is to pull a wiring diagram, follow the lines, and use it to make a little cartoon (aka diagram) of the circuit. Then, I can start w/ a place in the circuit (the battery, the ignition switch, fuse box, whatever's convenient), make sure I've got voltage there, and then just keep checking voltages as I travel down the line. When I find a place where there's no voltage, then the problem is usually between that last place I checked, and the one before. One other thing, you'll notice I talk about checking voltages on live, powered-up circuits. Not breaking out the ohmmeter and checking components. Trust me on this, there's a reason: the ohmmeter will measure how much resistance a component has against a TINY amount of current draw. Checking live finds out how it's working 'real world' style. I chased my tail with a main fuse on a '49 Plymouth that 'ohmed out' okay, but wouldn't p*** enough juice to run anything. Didn't LOOK blown, but the strap in the middle of the fuse had a hinky connection to one of the end caps. Check VOLTAGES and this won't happen to you. Sorry for the 'war and peace' novel, but I figured rather than tell you what the problem is (which would be a 'crystal ball' diagnosis anyway), it's probably more useful to tell how I would find the problem. One of those 'give a man a fish' deals... Good luck w/ the diag. Any ???'s feel free to PM; it's set to ping my email, and I check that at least once a day. -Bill
I'd always keep a working set of old tune up parts, points, condensor and rotor and even a "known to be good" coil. if I ever had a weird problem like that, I'd swap the parts one by one. Sometimes it would be one of those parts, sometimes not. Bob
I just had the same problem with my dual point distributar, when I put the new points in, I had one of the ends touching the bottom of the dizzy, causing a ground. Moved the wire a tad, fired right up. Hope you find your problem, always frustrating when something ain't workin' right.
Not sure if I'm thinking of the right thing, but once I had the wire from the coil into the distributor short out where it p***ed through the opening in the distributor body......that killled all power for me. You couldn't see the bare piece of wire without removing it from the distributor.
I changed the cap and rotor, no change. The spark from the coil is jumping about 1 inch the the intake manifold with the spark wire disconnected from the distributor. The rotor is spinning. Does having a spark at the coil rule out points and distributor ground wire? HELP I cant figure this out!
Do you have spark at the plug? If you don't and you changed the cap and rotor and you have spark at the coil that narrows it down to the points or condensor
I do not have spark at the plug, I already changed the condenser. I didn't change the points yet, they are clean without corrosion though.
Ok, as 440 Roadrunner previously said, you have proven that you have spark which means that the coil, condenser and points are working pretty much as they should. That means the problem lies down stream of the coil wire. Check the cap inside and out, Make sure that the carbon ****on inside that contacts the rotor is in place and not broken. Make sure that you don't have a bunch of condensation inside the cap. This will cause a no start condition but usually you do get some spark. You did put the rotor back in and it is in good shape? The older Delco distrubutors especially in 57 model cars were famous for breaking rotors if the engine mounts were a bit bad. One of the heater screws is/was sticking out directly behind the cap. I would take a serious look at the cap and make sure that it is clean, dry and not broken or carbon tracked and that there wasn't a bunch of corrosion in the terminals where the plug wires go.
Just one more question for clarification, when you get spark from the coil wire, it does continually repeat?...i/e spark-spark-spark-spark-etc... and NOT just "one" good spark?
How old are the wires. If they are old and unless they are solid wire there may be nothing but a few lumps of carbon inside the covering where the dirty string used to be.
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