The Stovebolt Site Forums The Shop Area The Electrical Bay No Spark

I was working on my 1954 Chevy 3100, everything was fine until one day it just would not start. Here are some specifics, I do have power at the coil (it is brand new) and power running to the distributor. The points, condenser and distributor cap are all brand new, as are the spark plugs and spark plug wires. Also the battery is fully charged. The main problem is that i have no spark and I am at a loss. Any insights would be appreciated, Thanks.

RCRJohnnie3,

Good job on troubleshooting so far. If the coil is new, the assumption is that it's fine. This would leave the points and/or condenser as the possible cause of your no-spark problem. You do have your rotor in...right!

Are you holding a plug wire near ground as someone cranks the engine to check for spark? I would check the point gap first as this is the heart of the spark so to speak. Good luck and keep us posted.

Stuart

Yea, I forgot to mention that i replaced the rotor as well.

I would check for power on the + side of the coil with the key on with a test light. If that test passes move the test light to the - side of the coil and crank the engine over the test light should flash also the coil should spark. If no test light flash points could be at fault. If test light does flash suspect faulty coil.

You probably dont have the wires connected to the points correctly. If the terms. are turned they can short to ground. If you dont have the special tool for that its hard to get them on correctly.

Check point gap . If points are not closing all the way You will not get spark good luck Pete

what wire(s) are connected to the points? I thought there was only the one wire connected to the condensor. Thanks.

starsfan,

The negative side of the coil (-) attaches to the insulated stud on the side of the distributor housing. Inside, that stud has a common connection with the condenser and one side of the points. The points are the switch that triggers the coil. The condenser is the 'sponge' that grabs the big spike of DC voltage to preserve the point surfaces as they open.

Stuart

Yeah, I was thinking "wire" to the points, instead of the metal prong/spade that attaches to the stud along with the connector from the condenser. Thanks.

Where should the positive side of the coil wire come from or go to? I am having the same problem with my coil, as it stands now, the wire comes straight from the battery cable, there is a wire coming out of the positive side of the battery cable, and that is how the old coil was set up. The coil get real hot when i hook up the battery, i am also working on the ignition switch, i do not think the wiring is correct on them.

av8tor,

The wire going to the + side of the coil is called the primary lead wire. It needs to be switched ON when the engine is running and OFF when the engine is shut down. This task is normally performed with the ignition switch. A wire runs from a position on the ignition switch that is powered when the switch is ON.

If your rig has been converted to 12 volts, there needs to be some type of resistance in the powered wire to coil +. This takes the form of a ceramic resistor called a ballast resistor, or on more modern rigs, a special wire with built in resistance.

If you run 12 volts and don't want to deal with some type of resistance deal you can install a ignition coil that has the resistance built in. If you power your coil from the battery without a switch for long periods of time, you can cook the points and ruin the coil...as you noticed with the heat.

Does this make sense to you?

Stuart

I've read over this post several times trying to see if it would help me to get my 1950 216 started, but I am still unable to. I'm hoping someone here has some ideas. The truck is still set up with a 6 volt system, but I have replaced the battery and coil to 12 volts. I do get spark but can't seem to get her to turn over. There is great compression and everything seems to be in order. Any chance that by using a 12 volt battery I'm not getting enough amperage to start her?

NW5window My guess would be that you need to do a few things. First, pull the connectors off the battery, take some sandpaper, and lightly sand all the connection terminals free of any corrosion. Any wire mounting points, do the same (EG, ground wire to frame). Make sure the starter's connections are clean, and all the wiring to coil is bright as a button.

Something doesn't compute with that statement. Are you saying the starter won't crank the engine, or that it's cranking, but won't start? Just changing the battery over to 12 volts won't be sufficient- - - -you need to upgrade to a 12 volt coil, and install a resistor in the circuit between the ignition switch and the coil to prevent the points from burning in a short time. Running a 6 volt starter on 12 volts is OK, but don't spend a lot of time cranking or you'll overheat the starter.

If the engine is cranking, the plugs are firing, it's got good compression, and it still won't start and run, you've got a fuel supply problem or the ignition timing is wrong. The spark plug is supposed to fire as the piston approaches the top of each cylinder on the compression stroke. A quick way to check ignition timing is to pull the valve cover, watch the #6 cylinder valves, and roll the engine over by hand by turning the fan (clockwise from the front) until the exhaust valve opens, then begins to close. Keep turning. The intake valve (2nd. from the rear) will begin to open. At that point, the distributor rotor should be pointing toward the #1 cylinder plug wire. (Not #6!) Once you establish that the rotor is pointing toward #1 at the proper time, the rest of the firing order should be 5-3-6-2-4, with the distributor turning in a clockwise direction.

Once the firing order and timing is sorted out, the only thing left is fuel. Dribble a little gasoline down ther carburetor throat (Don't overdo it!) and the engine should start and run a few revolutions. With a good gas supply and a carburetor in good shape, it should keep running. Good luck!
Jerry

Thanks guys, I'll double check my battery leads, and the timing.

As far as the coil, I did switch to a 12 volt with a resistor between the ignition and coil.

When I try to start the engine the starter whirls and spins and spark gets to the plugs, but the closest to getting it started was a "backfire" through the carb.