Let me ask you guys this...

I replaced the terminal block last night with a new one. No change.

The red wire coming in to the coil comes from the key switch right? Through the coil and terminates at the terminal block with the condenser. Is this right?

The ground for this assy is that terminal block and it grounds internally to the distributor at the attach screw to the condenser. Correct?

The incoming red wire... Does that come from the steering column ignition switch? Is there anything that could have shorted between the coil wire and the "+" lead at the battery? Maybe under the dash?

The car DID run fine before I replaced the cap, rotor, plugs and wires and I did replace all of the original components I removed for the tuneup at some time over the last 4 days with no change.

I may have removed the "+" battery terminal first when I was disconnecting it for the parts changes but, I don't understand why that would make a difference. If it would make a difference, what could be damaged?

Come to think of it, the cooling fan is wired to come on when ign is on. I believe there is a ground tapped to the small wire coming off of the alternator going in the direction of the cooling fan. That is not a stock condition.

Is it worth taking a look under the dash to see if anything is out of place? While I have 12v at the red wire to the coil, can someone explain how I could the to make sure it is getting enough current? I have a standard multimeter but, don't really know how to use it except to check the voltage of batteries.

Any ideas of things I can test or check before that harness comes tomorrow?

Thanks

 

Well - if the battery is fully charged, electrical connections (both + & -to and from) are 100% and the entire dizzy assembly is sound/solid then is seems like the new wires may be the problem... since they are pretty much the only variable you haven't swapped back during testing. Any chance you still have the "old" plug wire set so you can reinstall/test it.

Did a couple quick searches (google) but couldn't come up with the application/production specifics for this wire set (Belden 700386)
you installed but it seems like Belden subsidiary of NAPA...but that is about it.

 

Thanks for the note Engle. It's something else. I put the old wires back on last night to try it. No change. I am going to pull the optima out of my 914 tonight and see if there is a "juice" problem although I tried a new battery on Monday and returned it as again. No change. Man this is a bummer! Is there any point in gaining access to the behind the dash wiring? Anything to see in there?

I feel I should trace the cooling fan wiring however the PO wired it to be on when key is in on position. I almost feel like something might be partially burned someplace yet still carrying some voltage.

Are there any important grounds I should clean or verify that would be important to ignition? If so, what locations? Maybe change the ground strap to eng/trans?

 

The only thing that I haven't mentioned is that sometimes the connectors (metal electrical tabs/pins) for the coil's connections can sometimes get pushed way "up" into the plastic cap (cover for the connectors and the stock HEI coil) and it might be possible that that is a poor connection. Other than that I don't have any extra info to offer you at this point - it seems as though something is getting "missed" or you have multiple "bad" parts that your swapping out for one another.

Nothing behind/under the dash to see there for an issue like your describing (spark getting weaker each time the coil fires).

If you've got 12volts at the coil's + terminal straight from the battery (as you indicated you jumpered it that way)that should be/have been good enough for testing to eliminate the rest ignition switch.

The main ground lug for the - (negative) battery cable is on the engine block, just above the oil filter & pressure sensor - you could ensure that its mounting bolt is "tight". As mentioned before/above make sure all your main electrical connections (main lug(s) on the alternator & battery too) are clean and tight and that your battery is fully charged. Your HEI coil takes ~ a minimum of +10VDC to "fire" off correctly. Rule of thumb - if you don't have enough power to "crank" the starter then you don't have enough to fire the coil off either.

Way to hang in there - - keep us posted on what you eventually find as the issue.

 

Cool amigo! I'll hit that stuff this evening and see what happens. I will recheck the connections to the coil. Would like to replace the female spade to the coil but I suppose that may cause an issue messing with the shielding to the connection? I hit the battery cable pads last night with a dremel brass wire brush. Super clean connection. Also did the same to the ground behind the battery tray. Removed that to check the fusable links. I'll pull the Optima out of the Porsche and try it... Hopefully it has the side post mounts... I cant remember. Will update again!

Ya know whats funny and tops off this whole deal? Apparently in my neighborhood here in Arlington, TX... a Corvette in the driveway attracts rats. 11 years in this house. No problem. two mornings this week, kids walking to school have attacked my mailbox. Can only be the Vette making the Jr High kids act like rats. You guys have vandalisim issues?

 

I have no idea what you mean....the local FL hooligan's handy work can be seen below. Parked the car outside 1 night - needed the extra room - had painted a replacement SMC targa in the garage that day and need the space.






Might I also recommend a locking gas cap.

 

Dude... That really sucks.

If I can make it home today without any vandalism, the neighbor kid and I are going to try and push it into the garage. Then the 914 is out there covered but, never been messed with till the Vette. :/

Here is mine:
http://forums.corvetteforum.com/phot...ta/1011/c4.jpg

 

Weak spark is usually wrong polarity of Pick-up to Ignition Coil or maybe a bad Pick-up (did you replace that too?). You need the right color wires: If the Pick-up is Clear or Black, you need Red and White for the Coil. If the Pick-up is Yellow, Coil should be Yellow and Red. Also, if you removed the Distributor, make sure it's installed at TDC, though that wouldn't effect spark.

 

Wow, those were cool flames. You should have put the same thing on the other side. Looks like some gal/guy is in love with you.

 

Negative on even touching the pick up. Initailly it went from running fine to no fire after a cap/rotor and plugs installation. Polarity is the same and the blades only go one way in the cap. White wire out of the coil is connected to the white tach wire. Red wire on coil to the red battery wire.

The car is cranking normally and fast. No fire at the cylinders or not hot enough spark to ignite combustion. The dash does dim pretty good during cranking. I noticed that last night. Might have always done that though.

It's gotta be current flow related but, I never messed with anything outside of cap/rotor/plugs/wires.

Are any of the plugs close enough to the main ground connection to where pulling the old wires or plugs could have knocked the main ground?

 

They did do both sides

thread:
http://forums.corvetteforum.com/c4-g...ree-paint.html

 

http://forums.corvetteforum.com/album.php?albumid=23069

Worked on it again last night. Made sur I had a solid connection on the hot wire to the coil. Tried tracing wires and thought I had located a bad relay as when i pulled it is had two cooked terminals. Exchaged and no change. The knock sensor is unplugged and was before all of these issues. Bought the car this way two weeks ago.

There are a couple of pics I just uploaded in the album above. Probably nothing informative to you guys but I do have a question on the two realys mounted to the firewall right behind the battery. What are those for?

Would the car still run if the ECU shorted? How could I tell if it was?

The battery light on the dash is staying on also. I notice that last night. when it does the system check, all of the warning lights go off except that one although she is cranking over fine... just not firing and getting very weak spark.

I am running out of things to try... any suggestions?

New harness from dist to ECU will come in today and I will try and install that and check the main ground tomorrow when I can roll the car back out of the garage and get the front end up and slide under there.

ignition ignition ignition.... I need some fire!! This gasoline in the tank needs burning!

 

Seems pretty weird that car ran before you did the HEI ingnition system overhaul and now she no workey anymore...even with all the old parts swapped back over.

The 2 relays behind the battery are for the MAF sensor (the Bosch MAF sensor is kinda pricey $$$) one is the "burn off" the other if for "power".

Seems like the "battery" indicator is telling you something.....best pay attention - look around - check & recheck all the stuff you may have messed with or bumped while messing with other stuff.

If you find nothing eles - perhaps remove the alternator and have it tested - most local autoparts stores can bench test it for free.

Looking at the pics you posted - the relay and the overheated relay connector that's infront of the battery on the wheel well is the "main cooling fan" relay. It seems like someone has been in that wiring.

Check the fuses in the fuse panel if you haven't already....sometimes its the simple stuff that gets missed.

If the knock sensor is not connected they you should have a constant "check engine" light or a stored trouble code for that.....the "check engine" light works? Turn the ingnition key to run without trying to start the car and see if it lights up on the center DIC switch panel assembly. You can do a "search" here on the CF to info on "how to pull stored trouble codes" from the ECM (yours is obd1) for your year range.

 

Just for fun try disconnecting the tach wire at the cap... Take the coil cover off the cap and see visually and test to see that the connects are made between the coil wires and plugs on the cap too

 

Out of curiosity, what does disconnecting the tach wire do?

 

I think you've hit the nail on the head with this post since the pick-up is what interupts the HEI coil's grounding.

 

Negative on the pick up. Remember... this loss of spark happened only after cap/rotor/plug swap. That's all that was changed before the loss of power. The original coil is back in and I did try and swap back to the original cap and rotor before trying to replace deeper parts in the dizzy. The pickup is the only part not changed out so far but, who knows? Doesn't really make sense. I didn't use a hammer and arc welder to change the cap & rotor...

 

http://autorepair.about.com/library/...l-fo-10967.htm

Hey guys... check out that diagram for me and confirm that #1 on the distributor is nearest to cylinder #7.

What would happen if all of the plugs were off 1 plug in the cap yet in the proper order. Would it still run or do nothing like it is doing? I just found this diagram and if it is correct, I may have cylinder #2 attached to distributor cap connection for #1... actually it is if the location is correct on the diagram.

Check your car if you would for me or if you know for sure... the most forward plug location on the drivers side, does it go to cylinder #1 on the drivers side or cylinder #2 on the passengers side? Both front cylinders nearest radiator...

If they were all off one but in the right order... would the car start or not?

Thanks... (doh!!!)

 

Ummmm... I didn't wait for a reply and tried it... it fired.

I apparently changed the plug wires one at a time but put the first plug one off. So while in order, seated the cap and all plugs rotated one cyl off.

Can I delete all of my threads on this... change my name... wear a bag over my fingertips for anonymity and start over???

My car is back , I learned a lot about ignitions and a lot about the components of this car so it's not a total loss.

 

Well - at least you finally got it...way to hang in there.