Hello everyone. This Vette is a rolling project for my youngest son and I, it will be his some day. (when i die of course! LOL) I have been driving it right along since I got it in Febuary, even made a road trip to Miami from Orlando. We washed and waxed the Vette Thursday evening, pulled it into the car port, removed the top. No signs nor indications of anything wrong. (Drove it to work and back) In the morning it would not start, cranked over, no spark (checked 1,3 and 6), had plenty of fuel going to the rails. Plugs and wires are new. I replaced the cap, rotor and coil and still have no spark. All of the fuses are ok. Rotor turns also. Looked for visual defects as pinched wires, bad connections and found nothing. I have a 1987 Corvette service manual and have followed everything I could find in reference to my problem. I am considering changing the pick up coil today, would this be the cause of my no spark condition? If anyone see that I am missing something, please let me know. Oh and I am not getting any codes thrown, I found out why, bulb is missing with its holder, going to get one of these also today.

 

I suggest you not just throw parts at your problem without a diagnosis. Take another cruise thru the FSM and you should find diagnostic info that will help you. This is how the dealer techs do it. Remember, C4's are practically antiques, and the dealer likely has no one on staff who has ever been under a C4 hood.

 

Thank you for your reply. I am running though my diognostics again right now. The parts I am replacing are things I want new anyway, while saving the old ones for emergency situations.

 

if you are on chart c-4 (91 fsm) 1a will suggest unhooking the four term est/ECM connector, comes off **rear of dist. if you have spark, it indicates pick up coil.

joe

 

Thanks, it is on C-4A in my book. It appears that I need a new pick up coil. With today being Sunday I have to wait until Monday to pick it up. I will post to reflect the results after installation. I already have the pick up coil removed from distributor now and it looks sad. Insulation on each side of the wire wrap crumbled in my hand. Thank you for your info, as it was able to guid me to the right page, I was on the ignition systems section 6D4-5.

 

the Haynes Manual is superior to the fsm for this hands on stuff, easier to follow, my opinion. sounds like you have some experience! I've worked on pre HEI dist many times, had them apart, but never had the need to take the hei down.

6d4-9 in my 91 has details to check pickup coil.

I hope you marked the distributor housing and TWO rotor positions before removing it? makes dropping it in easy and accurate.


saludos, joe

 

Welcome aboard CPL , sounds like a bad ignition module (you should replace it while you are there) if you replace it make sure to coat its base with the grease they come with.
Test the current module to see if its good or not before buying a new one.

 

Hope you did not pull Dist. I agree with Calderone. Replace ign module and see what you have

 

If a new pick up coil doesn't work:

I would first establish that there is 12 volts at the hot lead going into the distributor. May or may not be likely but it's an easy check and costs nothing. It's possible with no spark at all there's no power going to it. I would then examine the distributor for a frayed wiring harness. If the harness is frayed then the module probably shorted out. Whether or not its frayed I'd have the module tested. Autozone can do that for free.

 

Well, I did end up pulling the distributor. The problem ended up being the pick up coil and removal was required. I would like to thank Joe for guiding me to the right page in my Manuel. All of this was great experience for my 12 yr old... He got to re install the distributor and then fire it up. Runs great now. Just a note! We decided that as long as we were that far into it, that we would change out the module also. I love this forum.

 

corvettecpl, if you can diagnose a root cause, dissasemble a distributor, and reinstall it in the proper location, you are WAY ahead of the average diy'er! if you follow this forum, there are many posts from people who tear the engine apart but can't install the distributor.

having a young grandson experience it is further blessed, as you know.

the systematic, rational approach is best, but generally is not followed. the fsm leads to a conclusion, and you may notice that the very last recommendation was "replace module."

also, the Haynes -which most people ridicule- shows how to verfy the pickup coil with a meter, but the fsm does not -at least, not on that chart. it does give resistence values on page 6d4-12 in the 91 book.

as I said, never had reason to tear the HEI down, but have removed distr several times in the 91, for various reasons, and once to verify the components with a meter, pre-emptive checks, for the day it should fail. I like to learn somethng every day.

thanks for sharing your experience.

saludos, joe

 

Joe, I like Haynes books, they get you started in the right place. They sometimes do not go far enough for what I need. I have a Haynes for every vehicle we own and did own! LOL Changing the plugs on my wifes Xterra would have been imppossible with out it. I would have never found number 6 plug. Mirror, 2 swivles, 3 extensions, plug socket with a new rubber insert and alot of patience! IF you dropped the plug you were screwed. Anyway, we will be tackling several up coming projects on the Vette soon. Example: right side window regulator... Left is done. Who ever owned the Vette before me tried, bought new interior parts, carpet, dash, digital dash ect... They just did not install anything correctly. It looked like hell inside. It is getting better, mechanical items and drivability 1st. My 12 yr old son already can trouble shoot our 3 liter mercruiser engine by himself. He found an electrical issue on the ignition secondary circuit that for some reason escaped me. It ended up being a dollar fuse.

 

Joe I was one of the guys who said module. I have been in this business for ove 35 years. Running a fleet of over 200 vehicles. I have only seen about 2 Gm pick up coils fail in my life and they both were for the broken wires coming off them. Some resopnces you get on this form are from people who have been there and done that. Whet he desribed was tipical for GM module failure. For about 15.00 it really should have been part of his tune up anyway. And honestly not trying to knock the OP but he replaced 2 parts a one time so how are we sure it was the pick up coil? Hanes and the other manules are fine for gerneic things. But when it comes to testing, removing parts. chaseing wireing faults and diagrams. there is no replacement for FSM.

 

073, I wasn't referring to this thread, exactly, but to the "natural" impulse to replace parts without doing the failure tree, whatever, as the fsm does. No offense meant. I'm sure you see it every day on some problem or another. Every miss or performance issue is injectors.

I didn't suggest what it might be because I have no experience working on HEI's. I was reading the book at the time, and advised him about the first test for no spark. I have to stick with my comment, since the fsm leads the way, and I don't know for sure if the module "normally" causes no spark, or other symptoms.

Your experience may point you to the module 90% of the time, but one can get a dozen suggestions on what it might be. The fact is that it is a leap of faith, and could be expensive, depending on the component. The first reply he got was to verify the problem by checking, not throwing parts at it.

Seems like he did that. I would have no choice, since I have changed parts and recently checked some components but never verified a defect in HEI.

I had the Haynes when I got the car, and know its limitations. It covers too many years. The FSM, on the other hand, is meant for GM trained techs, not guys like us, and leaves out a lot of stuff. What could be a paragraph often is a sentence.

I also wondered about replacing two parts, but he said the coil had insulation off the wires. One day, he can put the module back in to see what happens. Also the coil

saludos, joe

 

You are right see it all the time on here and elsewhere about replacing this or that. I did not mean to offend you. I was just trying to explain why I said module so fast. What he described was just the way a bad module does fails after car is shut off,and no fire. plus it is a high failure part. And like I said only seen a couple pick up coils bad and they were wireing issues. Also and this is just me knowing what I know. as soon as I knew I had 12 volts to the cap and no fire I would do it again. for $15.00 not a great loss. And this is coming from very old school though of mind that you don,t just throw parts at things.

 

appreciate the discussion, guy. I'm old but still can learn. I speak with confidence, as you do, about things I have experienced, and still am wrong sometimes. memory is the problem.

I had no idea until now what a module cost. saw one in Echler's for about $115.

my curiosity is why the fsm does not suggest the most likely causes, so that can be looked at first, as it does on "no crank no click," going directly to the purple wire on solenoid.

as I said, being truthful, I was commenting on the general approach, rather than your or Calderone's remarks. my point should have been that the systematic approach will work better for the problems with which we are not familiar.

in hindsight, I should have left the comments out. one of the big limitations of e mail and internet is that words appear harder than intended most of the time, because we don't see the "body language." that's the reason for the smileys.

 

FSM 1987 corvette manuel chart C-4A sub section 1A stated disconnect EST connector and check for spark. I disconnected EST and achieved spark - results faulty pick up coil. The only problem I had was incorrect pick up coil was in the right box at auto zone, caught that right while in store. The right one was delivered an hour later from another store, i am glad Auto zone is only down the street. I later replaced module as so everything in the distributor was new, but made that decision after we had it running as I did not know how long it had been in. I was hoping it would have been the module though, I hated the thought of having to disassemble the distributor! LOL Anyway, I would like to thank everyone for thier comments and insight. Time for a beer.

 

corvettecpl, hooked073:

there is an interesting, old thread posted today, by My1st, "injectors no pulse." very similar to your problem.

the posts were intelligent, and pointed the guy to the most likely solutions. evidently, someone convinced him to change to a small dist with a remote coil, after he had -eventually- verifed that the pickup coil was defective.

no subtle message here, just thought it was interesting.

saludos, joe

 

Joe I was part of that post and worked with him a couple of days on here. there is good information in there. You will also noticed I gave the same advice as I did here. There after that I directed him to the pick up coil. and described what to look for. My opinion was to repair what he had after the problem was locaated. But he wanted the smaller dist..

 

Yep, we agree, dude! I learn a lot from going through old threads, watching the logic and the experience at work. Many people tried to steer him -and not criticizing him- but once the mind is made up, you know the drill. I read your comments, and can tell when people have the mechanical mind, but are not locked in to one view. The voices of experience, who understand that many things are possible with computers and electronics.

Once the guy heard of the "divorced" coil, he had to have it, even tho' he had replaced the entire HEI except for the defective component!

Thought you'd remember.

saludos,
joe