interesting problem occured the other day....by interesting I mean F(*#& I want to blow this car up!

Anyway, I digress.

car running great...electric fans kick on, and poof, all the juice gone. NADA. Nothing. No power to anything. I had some wiring shorts not long ago, so I attributed it to a short in the headlight harness (the one with issues). I ripped out the old headlight harness and ordered my new one. In the mean time, I pulled the dash gauge area out to check the wiring in there and everything looks good except the main hot lead to the ignition cylinder (read wire coming from the headlight harness junction). I decided to just replace that wire...ran a new main hot from the battery junction block to the ignition hot. Everything fired up fine.

next...

I got the new harness, plugged in all of the lights up front, plugged it into the firewall block, turned the key and everything fired up fine. Turned the headlight switch on...POOOF. Black out. THis time, I have juice, but the car will not turn over.

I've disconnected the new harness in fear of a short in there, but no luck. I've checked the ignition switch itself and its fine. I've got 12V to the coil in the ON position and and 12V to the starter on START, but the motor will not fire. An indicator (to someone that knows more than me) might be that when the starter is cranking, the lights in the car (dome, dash, etc), flash in line with the starter motor cranks.

I've got an MSD dizzie and MSD blaster coil. To me, sounds like my coil is cooked.

ANY thoughts would be greatly appreciated!

What is the voltage to the ignition up front while you are cranking?

Dimming lights indicate some degree of voltage drop. If the voltage drops far enough the ignition will cease to function.

The new wire you ran... sounds like you ran direct and bypassed all the bulkhead and factory wire setup? I hope you put a fuse out close to the junction block on that wire?

Steve

fired the fusible links in the wiring harness.

The voltage at the + on the coil drops to about 9.5v the batter is a bit low from all the cranking. I didn't put a fuseable link in yet as this is still in testing/reworking. If I've got 12V at the ignition switch and 9.5-12 at the coil on cranking, would that still suggest that some fuseable links are fried? Where are they in the harness?

Thanks guys!

Check your main ground cable at both ends and check the ground straps between the engine and body. I''ll bet you find that the main ground wire isn't making a good contact at the engine end or it's gone bad inside one of the crimps.

Easy way to check is to connect your meter to the battery negative post and to the engine block on a clean location and then get someone else to turn the key to start.

If it's not the ground wire then it's likely something wrong with the power feed wire that comes off the battery and goes to the horn relay. It's a 10 guage wire I believe.

Peter

I've got a ground from the battery to the fender and to the block itself and a ground strap from the block to the firewall. Are you saying to put the negative meter on the - post and the positive meter on the block? What should I see with the key turning on?

I've got a ground from the battery to the fender and to the block itself and a ground strap from the block to the firewall. Are you saying to put the negative meter on the - post and the positive meter on the block? What should I see with the key turning on?

You've got it. If the cable is good you should read almost nothing on the meter. That's because there won't be any voltage to talk about between the battery post and the block. If the cable is bad voltage will go high (+) because the negative post is true ground and the block isn't grounded (bad cable).
Actually I would disconnect the small ground wire from the right inside fender when doing this test. That small wire along with the ground straps can fool you with some invalid results.

I took the ground strap and fender ground off, Im reading like .24v (1/4V) on the block on cranking. Now what? Is that OK or too much?

I put a new coil on to test...no change

Gents, I HAVE to get this thing running tomorrow...or my wife might have my head. This is my daily driver, or it's supposed to be, and right now, it's my daily driveway ornament.

At this point, I'd settle for just hotwire rigging it to get it firing. At BARE minimum, i think I need:

hot from the battery to the ignition switch
lead from the ignition switch to the starter
lead from the ignition switch to the coil

excluding any of the other necessities like headlights, brake lights, etc., that SHOULD be all that is needed to fire the motor, right?

Some questions:

does the ignition switch need to be in the dash for a ground connection? Right now, it's just dangling while I work through this

i have an MSD dizzie. Is it possible that it died and if so, how can I check it? I swapped coils to no avail, so the coil is pretty much excluded.


What do I do next? I have the entire dash pod out. I have the headlight harness completely disconnected to eliminate that from the possible problems. I'm dying here!

Thanks again for the help!

The power to the starter motor goes through the main battery cables between the battery and the starter motor. So, for it's operation to affect the power inside the cabin of the car to the extent that the lights flash as it's turning the engine over tells me that you've got a problem very close to the battery. A wiring problem under the dash wouldn't be affected by the starter motor operating.

The power inside the cabin comes from the 10 guage wire that taps off the positive terminal of the battery. I believe in your car it runs to a block behind the battery, across to the horn relay, to the terminal block on the firewall and then finally splits in the fuseblock and runs to the ignition and light switch. The power return is via the ground straps and main ground cable to the negative battery terminal.

So, for you lights to cause all power to cut out means that it's something in that main power feed between the fuseblock and the battery. If you replaced the light harness then it's not likely the problem. So, this means the problem is at the battery or in the fuse block/terminal block area.

You never said what you did after you lost all power to get it back.

The meter trick will work for any area. For example, connect one lead to the horn relay and the other to the fuse block. Since both points where the leads are connected are supposed to be at the same voltage you shouldn't read any voltage during this test. If you do, the problem is between the two spots you were measuring. Put a load on the circuit when doing this or the test is meaningless.

Peter

Thanks Peter. The car is setup like this:

battery connected to the starter motor (of course)
hot lead from the + post to the horn relay via 10gauge wire. this is also where the alternator makes connection.
From that relay, the load is carried into the fuseblock as you suggest, then to the ignition switch and everywhere else. Since I had issues in that harness/fuseblock (same harness as the headlights), i ran a new main hot feed into the car from the hornrelay right to the ignition switch.

All of those wires seem fine and are brand new. Could issues in the lights during cranking also indicate a problem in the solenoid wire coming from the ignition switch to the starter? If that were grounded somewhere, that could do it to right?

I have a new high-torque starter on it with a 2-prong harness. I didn't install the starter, so I don't know exactly how it's wired up. I assume one of the prongs carries current from the ingition switch. Should the other prong be for a ground or to carry that current then elsewhere? I guess I need to unwarp that harness and see whats what.

After I lost power, we pulled the car home. I removed the headligh harness, opened the dash up to check everthing in there. Made a couple of bandaid repairs. I think the problem was in the hot lead to the ignition switch. It was in bad shape. I snipped the end and recrimped a connector and i think i had juice back at that point.

Now for clarification on the meter test, I can touch the - meter to one spot (hornrelay) and the + meter to any post on the fuse block, put a load on the battery (since I have no headlights hooked up, I could crank the motor). If I see ANY voltage, there is a problem? Like I said, I show .25v on the block test...is that in a tolerable range? Is there ANY tolerance or should it show 0?

I really appreciate the help!

I would expect that your battery - to engine block volatage test should have read zero or something in the .0x range at a maximum. That would be battery terminals or cable ground connection to engine.

I would not expect electronic ignitions to work reliably below perhaps 10V but you can verify this by taking a spark plug out and seeing if you have spark while cranking. Would probably be a good idea to put a charger on battery.

As my dad used to tell me you need only three things for an engine to run: fuel, compression, and spark. Take one of these away and all the joy stops. You probably still have compression and fuel so you are left with spark.

It should not matter if the ignition switch is connected to the dash. You are switching power for ignition and starter so no ground connection is required.

It should not cause you problems right now but I would revisit that ignition switch connection you made. I would want to solder that connection rather than rely on just a crimp on terminal.

As to hotwiring... you could try wiring ignition up direct to battery for a test. If it works that way then you would know you really have a wiring system problem. If it doesn't work then you would know that either battery voltage has dropped too far or the ignition module/dist is toast.

Is the starter spinning the engine? It sounds like it is. If so, add a test jumper wire straight from the battery (+) terminal to the coil. This wire would replace the ignition wire that comes from the ignition switch/fuseblock.
Now you have a solid 12 volts to the ignition system. Don't leave it on too long without the engine running. The coil won't like it.

Yes, the starter is spinning the motor. I added a jumper from + to + on the coil. No luck. I've bypassed the fuse block already for that line.

I've got upwards of 10v at the coil on ignition. I have a battery charger/jumper and with a boost, still nothing.

I've got fuel and compression...I'm sure it's electrical. WHERE?!?!

I've swapped coils with no luck, so it's not the coil. I guess I'm down to the distributor?

OK, back when the die first happened, it occured when the electric fans were turned on. I disconnected the fan switch from all juice, and I was able to now get the motor to fire...barely. VERY rough and have to carm the throttle and pump it to keep it even stumble running. It backfires, stumbles, spits, and dies as soon as I stop humping the throttle. Timing? I've tried turning the dizzie while trying to crank it to no avail.

is this progress?

Is there spark?

Try putting a GM HEI distributor in it. One power connection to connect to make it run.

Peter

I have an inline spark tester...little glass tube thingy that plugs in line of the plug wire. It flashes..all be it more faintly than I would expect it to, but it does appear to be firing at least a bit.

What dizzie do I ask for at the parts counter (make, model, year, etc). You know how those guys are. It doesn't require a control box or anything? WHat are the connections on it?

Thanks again Peter (and all)

No idea where you are located. Have a couple of GM distributors tucked in a box you could try. Still common items around here at the junk yard. 76 Camaro would be one model.

Thanks. I'm in South Florida. So '76 Camaro...good start. But I know with that they'll ask for motor size, A/C, mother's maiden name, etc. Any small block '76 Camaro?