1989 C-4. Was driving & starting fine. Parked for the evening next morning cranks but won't start. There was no spark. 2 days later for the heck of it tried to start, and started. Very confused?

 

Start with a basic tuneup. Plugs, wires, cap and rotor

 

Icm

 

agree

 

No Spark I'd pull the Dist Replace the Pick-up coil and Module
Will save ya a Tow. Just went thru this crap with my 85 HEI
Started with hot restarts with a crank no start. No Spark
2 days latter Just wouldn't Run. One by one I replaced and in this order
Module-Coil Then the pick up coil
Will be doing brass insert cap and rotor with wires and plugs
If you cant or just don't want to mess with disassembly of the HEI
Complete Dist are cheep
Also don't forget to check for a small pinhole in the rotor, yea it happens somehow sometimes and causes no spark to the plugs

 

How did you determine "no spark"? Did you test it at the plug level? IDK how to do it on a HEI system but I have a small cap so I can test it from the coil. If it starts and runs, also check if the plug wires are leaking. How old is the distributor cap and rotor? Take it out and are there boogers hanging off the terminal? They might need to be changed too.

 

Did every thing Cudamax mentioned expect pick up coil. I will custom paint your car and make the body perfect, but I am not a mechanic. Maybe a new distributor is easier?

 

In response to aklim. I used a spark tester, one lead to wire other to plug, if it light in the middle I have spark. I did change module rotor cap and coil in that order. Still no spark.

 

If you have no spark and changed everything you said, either you have no power going to the distributor, or you have no pulse/signal from the pick up coil. EVERYTHING originates at the p/u coil; it is your "now, now, now, now, now" for spark, injection, tach, "Crank" signal...it is the foundation for running an EFI engine. If you have a way to test for tach signal or injector pulsing, then you can confirm the functioning of the p/u coil.

 

I'd bet on the ignition module before a pricier ICU. Never had an ICU fail, in ANY car. Plugs & wires are more likely to degrade, not just cause a sudden and total no-start.

As Tom said, troubleshoot, don't just throw parts. Intermittant problems are, obviously, much harder to fix. This one may or may not be heat related and e-parts, while rather robust, can get random before a total fail. Ensure at least 10vDC during cranking.

 

On certain year Corvettes the ECM waits until it sees oil pressure before firing the coil. On my 1988 Coupe it was a loose connection that caused my intermittent starting issues.

To check this, follow the intake plenum back to the rear where it come close to the firewall. You might have to remove the cover that goes over the distributor to see the oil pressure switch. On my 1988 the oil pressure switches are attached behind the plenum and above the bell housing. If you want to you can jump the two terminals together to verify that the car is seeing oil pressure.

Somebody had a similar problem on my car previously as I found the connectors had been replaced with the wrong size/color and they were not crimped very well. The wires were loose in the crimp and would slide right out if pulled. When the oil pressure switch is not telling the ECM that there is oil pressure inside the engine, it simply would make no spark.

After replacing the crimp connectors with the proper size and crimping it properly my connectors are now tight and that issue is off my plate.

Also check the two wires that attach to the base of the distributor. One of them is a Red wire that supplies power (12 Vdc) to power the distributor. The wires attach on the drivers side of my distributor. On my car the locking tab was broken and this will certainly stop you whenever the power wire shakes loose. I bought a new GM locking connector from NAPA and solved that one.

I can't paint a car very well but I have been known to fix a few mechanical troubles once in a while.

When you identify the problem please post what you found as this helps all of us here on the Corvette Forum!

Good Luck with your Corvette! You will be driving it (reliably) in no time at all!

 

No. That is not true. There is NO year Corvette that does this, when operating properly.


OP needs to check for a crank/tach signal.


.

 

 

mine was doing random starts and no starts. The security wire on the key was broken. However mine did not crank at all.

 

I have one here you can have free. We thought it was bad and put in a new one which wasn't my issue back then so the old one works
don't forget the greese

 

I have changed the ignition Control Module, Coil, Cap & Rotor. Still no spark. before I attempt the pick up coil what is the proper way to verify it is not good? Also I attached my ohm meter black to negative battery terminal and red to the BAT on the distributor turned key on and measured 11.6 volts is this correct to check the power from ignition switch?

 

here is what i did.

https://youtu.be/rc9b0prqzKs

 

^^Nice test!

 

ha! i forgot i mentioned you in that vid.

that was extremely out of my comfort zone at the time. but id do it again in a sit second to diagnose my diz. so easy.

 

That's cool....you "moved the rock forward" with your comfort zone. I love it.