Topic: no spark !!
in Forum: C3 Engines
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
I have a 1976 covette that has been sitting for 1yr - I went to start her the other day, but she will not start. The car is turning over, but won't start - I did see that I am getting fuel, but no spark. I have replaced the p/u coil, distributer cap, rotor, ignition module & ignition coil, but nothing has solved the problem - still no spark. I also put a test light on the main iginition cable & I am getting power. The battery is dead (of course) & I am trying to jump the car first, then I will purchase the new battery. Please Please solve my problem. Let me know if anyone requires further information.
Thanks for the help.
SPONSOR AD:: (Our Sponsors help support C3VR)
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
I can only relate what happened to me and my '69 once.
A similar thing occurred...no spark. Everything looked correct but still no spark. When I was inspecting everything, I had the chrome cover removed from the shielding around the distributor and coil, I decided to try again to start the car and it fired right up and ran fine...like nothing was ever wrong.
To inspect everything again, I reached over the distributor...didn't touch it...and I got the electrical shock of my life! I felt like I had to run into a dark room and check to see if my n_ts had turned into night lights!
What had happened in my case at least, was a pinhole had formed in the coil wire boot and the spark was grounding out through the RFI shield cover instead of going through the distributor to the spark plugs. When I had my hand near it the spark jumped to me.
Replacing the coil wire boot fixed my problem. I don't know if you have your RFI shield in place or not, so your problem could be completely different. If your shielding is in place, try it without it.
A similar thing occurred...no spark. Everything looked correct but still no spark. When I was inspecting everything, I had the chrome cover removed from the shielding around the distributor and coil, I decided to try again to start the car and it fired right up and ran fine...like nothing was ever wrong.
To inspect everything again, I reached over the distributor...didn't touch it...and I got the electrical shock of my life! I felt like I had to run into a dark room and check to see if my n_ts had turned into night lights!
What had happened in my case at least, was a pinhole had formed in the coil wire boot and the spark was grounding out through the RFI shield cover instead of going through the distributor to the spark plugs. When I had my hand near it the spark jumped to me.
Replacing the coil wire boot fixed my problem. I don't know if you have your RFI shield in place or not, so your problem could be completely different. If your shielding is in place, try it without it.
Yes,
the shielding has been removed. Thanks for the info though.
Your car has an HEI distributor. This is fairly easy to diagnosis.
Disconnect a few plug wires and crank the engine to make sure there is nothing coming out of the distributor. You could just have bad plug wires, or shorting spark plugs. Either one can happen after sitting.
First test for power on the red wire on the side of the cap with key on. If that's okay, leave the wires connected and remove the cap. You may need to pull some plug wires off the cap, but keep the wires on the side connected.
Make sure all of the small wires are in good condition.
Put a test light or dwell meter on the brown wire next to the red power wire. This is the tach wire. Crank the engine. If you get a dwell reading or the test light flashed, the pickup and module is working properly.
If so, hold a jumper wire near, but not touching, the center contact in the cap. Crank the engine. If it sparks, the rotor is shorted and stopping spark from leaving the distributor. If it does not, replace the ignition coil.
If the brown wire did not pulse, disconnect distributor pick up connector from the ignition module. With the key on, use a jumper or screwdrive tip and repeatedly touch one of the contacts on the module, pulsing it to ground. If nothing happens, do the same thing with the other contact on the module for the pickup. If the coil now fires, replace the pickup. If it does not, replace the module.
Just one addition. If you did not get the spark, before replacing anything, disconnect the brown wire from the cap and crank the engine. If you get spark, something is shorting the brown wire to ground.
That is all there is to the HEI. Fairly simple once you know. Feel free to ask more questions, and let me know what happens.
Elvis is in da house
You go Ken
eboThanks for the information. I have already replaced the p/u coil, distributer cap, rotor, ignition module & ignition coil, but will retry all these tests again tonight. Forgot to previously mention that I had replaced several spark plugs & wires (the easiest ones to get to). hopefully it is the brown wire you speak about. I will try tonight & let you know what happens. Thanks Again.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Make sure there is 12v+ on the large, red wire on the dist. cap connector while cranking. You can have voltage there with the key on, but loose it when you turn the key to the "crank" position. If you loose the voltage while cranking, you'll prolly need to check into the ign. switch, or a connector issue. 
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
If you think that you have an issue with power on the red wire at the distributor you can pick up power using a jumper wire from the big red wire at the alt and connect it directly to the distibutor, this will give a test supply of power to see if it will start.
John
I tested the large red wire to the dist & in the on position it gives me 12+ volts. When the ignition is turned to start the voltage falls to 6 volts. I assume this means the ignition switch is bad ? or could it be more than this ? I was looking in a repair manual & on the '76 it appears I need to drop the whole steering column. I guess my first step is to try the test suggestion from acplus prior to dropping the steering column ?
When you tested the voltage did you have it plug into the distibutor? Unplug it and try it. Then go to the other test from the alt
Sometimes after years,,,the ignition switch rod doesn't have the switch make full contact, while stand on you head you can try to straight it out a BIT, or push it towards the switch or try turning your ignition cylinder(key) on and off a feww extra times.... also check the plug at the switch for burn markings. And if you can check your supply voltage to the switch.
John
in Forum: C3 Engines
SPONSOR AD: (Our Sponsors help support C3VR)