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I have a 1991 Camaro RS that I pulled the motor and have since reinstalled and having trouble getting it to start.
What I have done so far...
Replaced Distributor brand new
New Coil
New Plugs
I'm getting 12v to the coil
When I test the coil wire from the coil side and turn the car over, I get .16-2 ACV, which jumps to .4 and higher as I try to turn the motor over.
I've checked all four ground wires to the back of the motor, as well as the battery ground and the ground strap on the bottom of the car, and they all are secure.
Does the engine not crank, or does it crank but not start? HUGE difference in diagnostics depending on which failure you have.
Kinda guessing that it cranks, but won't start and run.
1. Does the distributor rotor turn when you crank the engine?
2. Have you ever removed and reinstalled a distributor before, and did the engine run afterwards? (i.e., did you install the distributor with the engine at TDC-Exhaust rather than TDC-Compression, or similar synchronization problems?)
3. Are the spark plugs worn, or fouled from excess cranking?
4. Is there power to the distributor module in addition to the ignition coil?
5. I've never heard of folks looking for AC voltage on the coil wire. I have no idea how that would be helpful. What is the resistance of the coil wire, and the plug wires? Insulation burned/cut/abraded?
6. Does the coil have enough spark power to reliably fire a spark-tester calibrated for HEI? There's multiple kinds of spark testers, avoid any that use a crappy light-bulb that glows to indicate spark. You want one that causes the spark to jump a calibrated gap. My favorite kind is
7. Is this "new" distributor made in China, with a lousy bottom-feeder ignition module included? Same for the "new" ignition coil. You're probably better-off with your original module and coil unless you can show that they're defective.
Yes, the engine cranks and fuel is coming through the injectors when I try to turn the engine over. Thank you for this list of items to go through, I plan going through each of them again tomorrow.
On the distributor, I’ve not but the person that was helping me has. We bumped the engine to get to TDC before removing the distributor. The distributor is a Carquest complete unit from Advanced Auto. The ignition coil was also carquest, not sure if that’s good or bad.
The spark plugs aren’t new but didn’t look terrible. I did replace the wires with new car quest wires.
The AC thing was a suggestion from someone else on this forum. I could have mistaken the advice when I checked I’ll look back.
I’ll get a spark tester tomorrow, and not a crappy one.
Thanks for your help, I’ll send an update post tomorrow
Still waiting for the Spark tester, should have it shortly. I did a test with the new coil to see if it had power. I connected my test light to the negative on my battery and touched the coil with the engine turn to the on position and have no power. Does this help point in a direction?
Where your probe is touching will not have power. That is the plug wire lead to the distributor. That red wire in the grey plug just opposite that dizzy terminal is where you test for power. It should have power with the key on.
Still waiting for the Spark tester, should have it shortly. I did a test with the new coil to see if it had power. I connected my test light to the negative on my battery and touched the coil with the engine turn to the on position and have no power. Does this help point in a direction?
On the coil there are three plugs
With engine turned on....
1.)Grey plug from firewall.
Red wire is hot
2.) Black plug -From the coil to one side of the distributor
With grey plug installed, the red wire going into the distributor is hot
On the coil there are three plugs
With engine turned on....
1.)Grey plug from firewall.
Red wire is hot
2.) Black plug -From the coil to one side of the distributor
With grey plug installed, the red wire going into the distributor is hot
You should have a White wire, could be off on color, going from the dizzy to the coil? this is your signal from the dizzy to fire the coil. You established power to both now you need to see if your getting a signal back from the dizzy. I am sure there is a multimeter test for this but you can old school this also.
hook everything back up. Remove the plug wire from the dizzy that goes to the coil, the short, center wire. Put a spark plug in the end that would plug into the dizzy. Ground the plug, you can use the center post on the dizzy or elsewhere. Turn over the car. The plug should spark if the coil is receiving the signal.
You could also check for spark the old fashioned way, put a plug in the boot, ground it to the engine and turn it over.
Yeah, an ordinary spark plug is better than nothing. However, it's a poor test of the voltage capacity of the coil. A spark plug in air takes very little voltage to jump the gap; and it won't jump the gap at all if the plug is fouled.
That's why decent spark testers have a huge gap--to compensate for the lack of 150-ish psi of compression pressure trying to snuff-out the spark. HEI spark testers have an even bigger gap than those for ballast-resistor ignition systems, to properly-load the ignition coil.
HEI spark tester on left, Ballast-resistor ignition system spark tester on right
Recessed center electrode of HEI spark tester at left produces larger spark gap, vs. visible center electrode of ballast-resistor style spark tester on right.
With no spark at the spark plug end of a plug wire, re-test at the coil wire going into the distributor. If you have no spark there, I suspect the coil, or--more likely--the ignition module.
But that assumes that the distributor shaft is actually turning, and the wire harness between distributor and coil isn't faulty.
Yes, the new distributer had a new ICM and before I bought a new distributor I just bought a new ICM and replaced it in the old unit and still didn't work
Before I took the engine out of the car everything worked which makes me think something is not connected after I put the engine back in.
I'll take the diagram and trace down all the connections.
For the ICM, the plug coming from the firewall (not the plug coming from coil)
When the switch is on, should one of these be powered up?
I do not believe so, at least you will not see 12volts. That 4 wire plug coming from the firewall originates from the ECM under the dash. The ECM controls the spark advance and those are signal wires so there is probably a very low volts that change slightly to adjust the advance. I am sure there is a multimeter test you can do to determine if it is giving a signal to the ICM but not sure what that is.
The 2 terminals at the top of the ICM, P&N, are those connected?
So after a couple of hours cussing...The Camaro finally turned over....
While the red (pink) wire was 12v when the key was turned, once you tried to crack it dropped to 7v...I peeled back some of the wire and tapped it into a constant 12v and she fired right up. Once the car was running for a second I pulled the wire from the constant 12v and the car still ran perfectly.
I still have some adjusting to do with the timing but its now running.
Thanks for your help, you taught me a great deal about the car.
03-26-2024, 04:46 PM
