Triple Carb Conversion + MSD Digital Ignition Problem... HELP!!

[thegroundlevel]

So I’ve been rebuilding my ’76 280z for the past few years, and I’m finally onto the carb conversion / ignition stage of the project.

I’ve removed all EFI harnesses from the car and installed a QuickCar rocker panel to control everything on switches. I also installed an MSD Digital 6AL and Blaster 2 Coil. Carbs are Triple Weber 40 DCOE.

I’m having issues getting the car to fire. As of right now, I have ignition power, fuel pump power, starter engagement, and engine cranking. But there seems to be no spark in the cylinders. There IS gas delivery though. This is where I need help…

I have read mixed reviews on how to have the MSD set-up. Orange and Black wires are going to my coil. That’s the obvious one. Then, I have tried both the Magnetic Advance option [hooked up the green and red wires coming out of my electronic 280z dizzy to the green and violet harness from the MSD (also, there’s a third brown wire coming out of the stock dizzy too… where does that go?)], as well as without, functioning off of the white wire from the 6AL going to the positive post on my coil. I have also tested for spark from the coil going to the distributor by removing the coil-to-dizzy wire and grounding the white MSD wire to arc a current. That works when my ignition is switched on, without cranking. Also had my buddy check a spark plug WHILE cranking, and he said the plug had no spark...

So what am I missing? Everything given my knowledge of basic wiring saw this as being pretty straight-forward, but right now I am totally at a loss. Expecting to hear that I’m overlooking something simple / stupid in my haste to get this car started, but I really can’t figure this out!

I’ve attached a few pictures to situate you guys a little better:

[NewZed]

21 hours ago, thegroundlevel said:

’76 280z

 

I have ignition power, fuel pump power, starter engagement, and engine cranking. But there seems to be no spark in the cylinders. There IS gas delivery though. This is where I need help…

I have read mixed reviews on how to have the MSD set-up. Orange and Black wires are going to my coil. That’s the obvious one. Then, I have tried both the Magnetic Advance option [hooked up the green and red wires coming out of my electronic 280z dizzy to the green and violet harness from the MSD (also, there’s a third brown wire coming out of the stock dizzy too… where does that go?)], as well as without, functioning off of the white wire from the 6AL going to the positive post on my coil. I have also tested for spark from the coil going to the distributor by removing the coil-to-dizzy wire and grounding the white MSD wire to arc a current. That works when my ignition is switched on, without cranking. Also had my buddy check a spark plug WHILE cranking, and he said the plug had no spark...
 

 

MSD has a wiring diagram and instructions.  Probably better to use that.

 

The first diagnostic test is to measure coil voltage with the key On and at Start.  No power, no spark.  Coil power doesn't come through the MSD box.  There are two power wires for 1976.

[NewZed]

L = Blue

[thegroundlevel]

53 minutes ago, NewZed said:

 

MSD has a wiring diagram and instructions.  Probably better to use that.

 

The first diagnostic test is to measure coil voltage with the key On and at Start.  No power, no spark.  Coil power doesn't come through the MSD box.  There are two power wires for 1976.

 

Ok, so referring to this diagram, I seem tobe bypassing the ballast block before the coil there.

 

I had assumed that power ON with the 6AL would be delivering power to the coil. Should I be running another connection at the coil posts to recrify this?? I’m wiring entirely from scratch here.

 

I just tested the magnetic advance signal with ignition ON by shorting the green and violet wires on the MSD (the ones that would otherwise be connected to my dizzy), and spark comes from the coil when I short them. 

 

thanks!!

Edited October 13, 2018 by thegroundlevel

[NewZed]

Make sure that the original module is disconnected.  And think of the MSD box as the make/break circuit on the grounded side, the negative side, of the coil.  The coil gets power, the MSD box lets current flow, the MSD box cuts the current when the trigger wires tell it to...spark happens.

 

Break it down in to the basics.

[thegroundlevel]

On 10/13/2018 at 3:32 PM, NewZed said:

Make sure that the original module is disconnected.  And think of the MSD box as the make/break circuit on the grounded side, the negative side, of the coil.  The coil gets power, the MSD box lets current flow, the MSD box cuts the current when the trigger wires tell it to...spark happens.

 

Break it down in to the basics.

 

Well, everything IS disconnected as far as anything that was ever on the car.  I'm entirely rewiring the car. Mostly everything running off toggle switches.

 

That being said, this is how I have everything set-up right now.

What is it that I'm leaving out?? Should there be an independent power line + ballast resistor before the coil unrelated to the MSD harness??

 

Otherwise, everything as far as MSD's manual is concerned has the set-up looking complete.

SO confused!

[NewZed]

I mis-wrote in my other post. MSD runs all power through the MSD box.  There's an ignition wire, red, and a "heavy" power wire, also red.  You only show one red wire, not real clear which one.  By your drawing, you're missing one red wire.  The BW and BL wires should both be connected to the thin red ignition wire, "original coil + wire".

 

Yours would be the "magnetic pickup" scheme.

 

 

[thegroundlevel]

Ok yeah! The thin red wire goes to my "ignition pwr" toggle on my rocker panel. So I turn that on, and the power from the heavier red wire turns on the 6AL box via the battery positive terminal (indicated by blinking on the box).

 

So, given what you're saying! That's probably what I'm missing. I should be running a wire from the thin red MSD wire to a ballast resistor and then to the coil positive??

If so, that might be the ticket!!

Edited October 15, 2018 by thegroundlevel

[NewZed]

No, you want to connect the BW and BL wires from your ignition switch directly and together to the thin red wire.  They provide the power to the MSD box with the key on and during Start.  

 

Power from the thick red wire passes through the box to the coil positive.  The thin red wire turns the box on.

 

If you're using a relay or switch for the thin red wire power, instead of the ignition switch,  and it stays on while you're trying to to Start, then their might be something wrong with the box.  It should spark if the thin red wire has power and all of the other wires are connected as shown.

Edited October 15, 2018 by NewZed

[NewZed]

There should be some troubleshooting steps here - https://static.summitracing.com/global/images/instructions/msd-6425.pdf

[NewZed]

14 minutes ago, thegroundlevel said:

The thin red wire goes to my "ignition pwr" toggle on my rocker panel.

 

Make sure that you're not losing power to your toggle switch when you turn the key to Start.  The ignition system turns off all accessory power during Start to give maximum current to the coil.  Start and Run are two different circuits.

[NewZed]

And, of course, there's always the possibility that you have a bad pickup coil in the distributor.  Confirm proper resistance and air gap.  But, you have two in there so you can always use the other.

[thegroundlevel]

4 hours ago, NewZed said:

No, you want to connect the BW and BL wires from your ignition switch directly and together to the thin red wire.  They provide the power to the MSD box with the key on and during Start.  

 

Power from the thick red wire passes through the box to the coil positive.  The thin red wire turns the box on.

 

If you're using a relay or switch for the thin red wire power, instead of the ignition switch,  and it stays on while you're trying to to Start, then their might be something wrong with the box.  It should spark if the thin red wire has power and all of the other wires are connected as shown.

 

I don't have those wires from my stock system in place anymore. That's where I'm getting lost here...

 

 Simply running off the switch panel for everything. There is no accessory vs. power ON engagement, like with a keyed ignition.

This is probably why the IGNITION 12v is the first, primary position of the switch panel next to the START button. The rest (only other one wired at the moment being FUEL) are acc buttons.

 

Now, if I wire the coil to the MSD power wire, will that initiate the firing of the coil upon START??

Still confused about how / what my BW and BL wires would be in my current set-up.

But I think I'm getting it!

 

(also, NewZed, your help thus far has been monumental for me - thank you!!)

 

[ATTACHED]

 

4 hours ago, NewZed said:

 

Make sure that you're not losing power to your toggle switch when you turn the key to Start.  The ignition system turns off all accessory power during Start to give maximum current to the coil.  Start and Run are two different circuits.

 

The lights on my panel stay lit, so I would imagine the power is not cutting during turn-over.

Edited October 16, 2018 by thegroundlevel

[ZHoob2004]

6 hours ago, NewZed said:

 

 

This diagram is all you should need. The red "from ignition key" wire goes to your on/off switch and connects the wire to 12v power. The big wires go to your battery in some fashion. Orange/black go to your coil. Violet/green go to your distributor pickup.

 

This is a completely self contained system and all you need to do is tell it to turn on (with the thin red wire)

 

Your starter button should only connect to the starter solenoid (and maybe a relay for your ballast resistor if you have one)

Edited October 16, 2018 by ZHoob2004

[thegroundlevel]

26 minutes ago, ZHoob2004 said:

 

This diagram is all you should need. The red "from ignition key" wire goes to your on/off switch and connects the wire to 12v power. The big wires go to your battery in some fashion. Orange/black go to your coil. Violet/green go to your distributor pickup.

 

This is a completely self contained system and all you need to do is tell it to turn on (with the thin red wire)

 

Your starter button should only connect to the starter solenoid (and maybe a relay for your ballast resistor if you have one)

 

Well this IS how I have everything hooked up, sooo...

[NewZed]

Measure resistance across the wires from the magnetic pickup in the distributor, with them disconnected.  You might have the wrong ones connected or have a bad pickup.  Should be about 720 ohms.  You won't get repeated spark unless the trigger is triggering.

 

 

Edited October 16, 2018 by NewZed

[NewZed]

And make sure the distributor is actually turning when the engine turns.  You're at the "don't assume anything" point.

[NewZed]

On 10/13/2018 at 11:14 AM, thegroundlevel said:

I just tested the magnetic advance signal with ignition ON by shorting the green and violet wires on the MSD (the ones that would otherwise be connected to my dizzy), and spark comes from the coil when I short them. 

 

The test that you did here shows that your MSD wiring was correct.  You're just not getting the voltage pulse from your distributor.

 

Your MSD wiring looks right, it's your distributor's magnetic pickup signal that is not getting through.  When you touch the green and violet wires together you create a voltage pulse that mimics what the distributor should do.  Focus on the distributor.

Edited October 16, 2018 by NewZed

[thegroundlevel]

5 hours ago, NewZed said:

 

The test that you did here shows that your MSD wiring was correct.  You're just not getting the voltage pulse from your distributor.

 

Your MSD wiring looks right, it's your distributor's magnetic pickup signal that is not getting through.  When you touch the green and violet wires together you create a voltage pulse that mimics what the distributor should do.  Focus on the distributor.

 

Yeah, I also did a resistance test on the magnetic pick-up wires off the distributor, and got a 709 ohm read-out, which I would note as being in the "approximately 725 ohm" category

Now, my next logical move here seems to be trying a reman distributor or better and seeing if it is in-fact a faulty distributor somewhere.

 

Everything else is hooked up properly, and my battery read at exactly 12V on the multimeter as well (obviously been some drain w. all my crank attempts, but 12v should be enough to start the car, no?) Guess it wouldnt hurt to throw it on a trickle charger for now?? Brand new Optima Red!! Ugh.

 

 

Here's a couple more pics showing how I have everything hooked up, for those confused by my doodle:

(coil hook-up, engine bay feat. magnetic hookup, and back of switch panel feat. small red MSD & start button)

 

Edited October 16, 2018 by thegroundlevel

[NewZed]

2 hours ago, thegroundlevel said:

 

Yeah, I also did a resistance test on the magnetic pick-up wires off the distributor, and got a 709 ohm read-out, which I would note as being in the "approximately 725 ohm" category

Now, my next logical move here seems to be trying a reman distributor or better and seeing if it is in-fact a faulty distributor somewhere.

 

 

You're almost there.  Your test of touching the wires together, which created a spark from the MSD box, shows that the last, missing, piece is the trigger from the pickup coil.  You showed that you have a good pickup coil.  The trigger voltage from the magnetic pickup is caused by a ferrous piece of metal passing by, the six bladed metal wheel next to the pickup coil.  If you have a sensitive meter, or an analog meter, or an oscilloscope, you can see the voltage from the pickup coil when the distributor spins.  Nissan even drew a picture of what the voltage looks like on an oscilloscope in the FSM, Engine Electrical chapter.

 

Find a way to see if you're getting that voltage pulse when the engine spins.  You haven't confirmed that the distributor shaft spins with the engine, for example.  Things slip or break or get put together wrong.  People have had the drive gear slip on the shaft.  People forget to put the rotor under the cap.  

 

If you're testing for spark at the coil main wire take the distributor cap and rotor off and spin the distributor by hand.  Or just watch it when you turn the engine over.  Or lift the distributor up and spin it by hand with the key on.  Lots of possibilities.  Focus on the triggering system.  One thing that might cause problems is if you have the wires connected backward.  Maybe switch the red for the green.  Usually it just causes timing problems but maybe the MSD is more sensitive and won't work with a backward waveform.

 

There's also an air gap adjustment that needs to be right to generate voltage.  Check that.

 

Edited October 17, 2018 by NewZed