Engine ran BACKWARDS! WTF!?!?

[AceOfDiamonds0]

First what I'm working with. I've got a 72 510 with the factory L16. I replaced the stock coil with a 3 ohm coil and swapped the points with an electronic conversion kit. I also put in some bosch 4 prong iridium plugs in just cuz i had them laying around. I just put in a new fuel pump and rebuilt the 32/36 weber thats on it.

 

Now before i put the conversion kit in the dizzy, my points kept backing out and would not stay properly gapped. Which is why I put the conversion kit in. After putting all the new goodies on it fired right up without any issues and ran like a champ. I test drove it for a couple miles and figured it was good to go. It sat overnight, i tried to start it and it wouldnt start. I found that the air/fuel mixture screw was out way to far and i fouled the iridium plugs. I put in some NGK plugs gapped at .035 and since then I've had very inconsistent spark and it will fire when i just turn the key to the on position or the off position. It actually RAN BACKWARDS after trying to start it. I tried to start it and it spit and sputtered for a few seconds then died and started running backwards and shoving smoke out of the carb for a few seconds until I turned the key off.

 

I am lost as to what could be causing this. My only guess would be a bad coil? Why would the motor rotate backwards after trying to start it??

[AceOfDiamonds0]

Ok i just had a thought. When I put the electronic conversion kit in the dizzy I had to reset my timing.

 

I pulled the #1 plug and found what I thought was TDC. Could I have timed it 180 degrees out of time? Set it to fire on the exhaust cycle instead of the intake cycle?

[banzai510(hainz)]

adjust the mixture and reset the timming. You using a timming light. adjust to say 7 thru 10 and see how that works.

then adjust the mixtyure also and reck timming with light.

 

make sure choke isnt saying ON

 

 

bad coil? coil fires when its told to or just dont work.

[AceOfDiamonds0]

I can't get it to run to adjust the timing.

[Zeusimo]

Car Doesn't Need To Be On

Pull Off Dizzy Cap, Turn Crank Pulley With Ign On

The Dizzy Will Spark, This Should Get It Close

[AceOfDiamonds0]

When I did have it running with the inconsistent spark my timing was at 9 BTDC.

 

I'm trying to figure out what could cause the inconsistent spark and the motor running backwards.

[banzai510(hainz)]

put the old stuff back in is one way to trouble shoot.

 

If you put that new 3 ohm coil in with the ballast resistor still attached that could have soemething to do with it.

I personally would keep the stock stuff in there(ballast and old coil) and not run that new coil. But since you go it. its a 3ohm and you will NOT use the stock ballast resisitor.

 

maybe it cutting out cause of the ballast but if you read the instruction right it shoul be OK. if hooked up correctly.

 

why dont you send close ups of the hook up.

[AceOfDiamonds0]

Yeah I took the old ballast resistor out when I put the 3 ohm coil in. I followed the instructions for installing the electronic conversion kit as well.

 

I'll have to put the stock stuff back in like you said and see if that doesnt yield any answers.

 

 

[banzai510(hainz)]

Ok IM going to wing this one going by the photo. I dont think its hooked up right
I see the red of the pertronix going to one side of the coil. Since its red I assume its the positive side.
But on 510 the blk/wht wire is the +12volts and that looks like the otherside of the coil So which is the Positive side???. So is the Pertronix wires hooked up backwards? I see 2 connection on each side of the coil.???????????
The - side only needs the wire from the Pertronix (Blk)So mean only 1 wire on - side coil!Thats it.If there is another wire than I assume its going to a Tach. Maybe disconnect this in case might induce a proplem.

Tachs? Why I had 4 510s and never needed one

the +side coil should have the blk/wht wire from 510(12v ON) and maybe the 12v START(Blk/Blu or maybe BLK/Grn) and then the red of the Pertronix so total of 3

[datzenmike]

Now before i put the conversion kit in the dizzy, my points kept backing out and would not stay properly gapped.

This could be normal point wear. Points should be filed and gaped at least every 5K and often sooner. If your capacitor was missing or bad you might need it every few hundred miles.

 

After putting all the new goodies on it fired right up without any issues and ran like a champ.

This tells me that everything is working as it should or close enough. Even if the polarity of the coil is reversed it will run, just that the spark jumps from the ground to the plug not the other correct way. I've even pushed badly flooded motors so the starter isn't dropping the voltage to the coil and it's also turning faster. Once it fires up all the gas fouling burns off.

 

I test drove it for a couple miles and figured it was good to go. It sat overnight, i tried to start it and it wouldnt start. I found that the air/fuel mixture screw was out way to far and i fouled the iridium plugs. I put in some NGK plugs gapped at .035 and since then I've had very inconsistent spark and it will fire when i just turn the key to the on position or the off position. It actually RAN BACKWARDS after trying to start it. I tried to start it and it spit and sputtered for a few seconds then died and started running backwards and shoving smoke out of the carb for a few seconds until I turned the key off.

The motor might kick backwards half a turn but it can't run backwards. For one thing the first valve to open after firing would be the intake. No motor will run long firing exhaust into the intake.

 

I am lost as to what could be causing this. My only guess would be a bad coil? Why would the motor rotate backwards after trying to start it??

Probably very flooded and hard to start. Pull the plugs, hold the choke full open, hold the pedal down and do NOT pump it and crank it for 30 seconds to dry it out. Clean and dry the plugs or replace them. (NGK not any other kind)

[HRH]

Except a diesel.   ;)  That's why the guys at the wrecking yard hated running diesels on the motor stand.

[datzenmike]

A two stroke gas or diesel can run backwards.

[AceOfDiamonds0]

The coil is hooked up right. The two red wires on the positive side of the coil are from the dizzy and the ignition. The wires on the negative side are for the dizzy and then one for the tach that I have installed.

 

I think I may have fried the coil in all this comotion. I hooked up a multimeter to it and had 11.5V on the positive side and 0 on the negative side. This is of course with the key in the on position. Are these right?

 

The plugs I have been using I only used once in my Z and usually I don't re-use ANY plugs just for this reason but it ran ok the first time so I figured why not. Never again will I re-use spark plugs.

 

Oh and I did put the points back in just to see if that was it and I had VERY weak spark at the points which is why I decided to test the coil.

[banzai510(hainz)]

I think I may have fried the coil in all this comotion. I hooked up a multimeter to it and had 11.5V on the positive side and 0 on the negative side.

 

that maybe the position of the pertronix maybe remove the - side wires and then ck with the coil. A new coils isnt going to go bad like that. Like I said maybe removed the tach wire.

 

Plugs? I havent bought a set in over 10 years and I use used ones all the time. sandblast them Maybe if I see a set lying around. I just make sure to get NGK or Nippondenso

[AceOfDiamonds0]

Yeah the only time I used something other than NGK was the bosch iridium plugs and they seemed to do alright but I trust NGK more than anything.

 

I tried removing the tach wire and still got the same results.

 

The coil isn't BRAND new I've had it on there for at least 4 mothns now and it was running good for the majority of that time.

[AceOfDiamonds0]

Ok so it just ran backwards again!! I filed the points and put them back in. Made sure all connections were good. Checked for voltage everywhere I could and I even got the points to give me good spark.

 

Now here's the retarded part. I don't get good spark at the spark plug unless the motor spins backwards! I have my buddy turn the key to start and no spark until the key goes back to the on position.

 

I have not changed any of the wiring since the last time it ran good. It only started doing this after I used the bosch iridium plugs and let it sit over night.

 

 I did notice that when I had the electronic conversion kit in, after I tried to start it, I turn the key to the off position and it sparks once. Like it lights any fuel that was in one of the the chambers.

[datsunaholic]

Sounds like your "start" spark circuit isn't functioning (that's the one that bypasses the ballast).  I had that issue once- truck would only start if I let off the starter.  Not enough voltage on the "run" circuit when the starter was turning.   It would occasionally roll enough to start once I got off the starter, but usually I just had to roll start it on hills.   At one point I got so sick of it I put a jumper across the ballast, started it (which worked), then pulled the jumper as to not burn out the points.  Never could get voltage on the ballast bypass "start" wire, the wiring was so screwed up (couldn't use the key switch either, which was part of the issue).   I solved it by going with a matchbox.

[AceOfDiamonds0]

I'm not running a ballast resistor right now. I've just got a 3 ohm coil because I had put in an electronic conversion kit for the dizzy.

 

Sounds like I might as well just get a matchbox dizzy instead of using the kit crap.

[datsunaholic]

No, I got that- what I was (badly) hinting at is that it's possible you have too much voltage drop at the coil when you're running the starter.  Caused by a combination of too much starter amp draw and old wiring causing too much resistance between the battery and coil.  Hence, no spark until you let off the starter, then it's flooded and timed wrong so it "kicks back" when the fuel built up in the manifolds ignites.

[AceOfDiamonds0]

Ok that kind of makes sense. But all of my wiring is new and I do mean all of it. I rewired the car about 6 months ago and yes everything is wired right I've gone through every bit of it multiple times making sure everything right. Everything works and it ran perfect a few days ago I don't understand how it can just take a shit on me over night. :-(

 

I did find something interesting just now though. My 3 ohm coil has 3 ohms of resistance but when I tested the voltage it has 11.9 going in and 11.9 coming out. Isn't resistance supposed to you know, resist some of that voltage?

[datsunaholic]

That's because the ground path to the coil (-) lead is open.  It's only closed (grounded) when either the points are closed, or when the EI module tells it it's closed.  Otherwise, it's an open circuit, so with no negligible current through the coil, the voltage potential is approx. the same.  Resistors resist current.  Voltage is "potential".

 

You'd get the same reading with a 3Ω resitstor if you hooked one leg to the battery and left the other leg disconnected.

 

You're getting 11.9 at the coil- what's the voltage directly across the battery?  Then, what's the voltage across the battery and then the voltage at the (+) terminal of the coil when cranking?  That'll tell you if you have a big voltage drop. 

[banzai510(hainz)]

The start circut. or by pass wire,

I dont know how its wired using a 3 ohm coil.

I would take the Blk/Blu(Start) wire and hook it to the + coil also if it isnt already. with the blk/wht(ON)

 

Here is why I would leave the stock 1.6 ohm coil and the 1.6 ohm ballast in place.

So when using the start circut you only going to a 1.6 ohm coil and the spark should be bigger.

 

when you using the new 3 ohm coil your still going thru 3 ohms with the starter circut thus harder to start.

 

 

put the stock coil back in and the ballst if you can figure it out as that wiring looks funky to me.

 

 

Nothing wrong with the Pertronix. I have them in all 3 of my Datsuns and never had a real proplem besides maybe the magnet ring tape wearing out of magnets falling out.

[AceOfDiamonds0]

Ok I haven't tested for the voltage drop at the coil yet I probably won't get to that today. But assuming that I do have the voltage drop at the coil caused by too much amp draw from the starter, would the fix be ro rebuild/replace the starter?

[datsunaholic]

You'll always have a voltage drop when cranking due to a saturated battery, since the amperage of the starter well exceeds the battery's full-voltage reserve capacity.  The key is how much voltage drop you have between the battery and coil.  If the battery and coil readings are different by more than 0.1V, that's a sign you either have corroded connections, too small of wiring between them, or too many things on that particular circuit.

 

The idea is to measure the difference between the battery and coil both when not cranking, and when cranking.  Cranking will always show lower numbers, BUT The difference should be about the same on both ends. 

 

 

Examples:

 

What you want to see:

 

Ignition off:

 

Battery Voltage: 12.3V

Coil (+) Voltage:  0.0V

 

Ignition On, not cranking:

 

Battery Voltage: 12.1V

Coil (+) Voltage:  12.0V

 

Ignition On, Cranking:

 

Battery Voltage:  10.5V

Coil Voltage:  10.4V 

 

The above would indicate a 0.1V drop to the coil, which is not uncommon due to the amount of connectors, fuses, switches, and possible relays that the current has to go through.  But more than 0.2V would indicate an issue of some sort.  I've seen cars that RAN with as much as a 2V drop, though. 

 

 

Now if you had this example:

 

Ign ON, not cranking:

Batt: 12.1V

Coil (+): 11.7V

 

Ign ON, Cranking:

Batt: 10.3V

Coil (+): 9.9V

 

That would indicate there's insufficient wire to handle the ignition circuit load, or a slightly corroded connector.  That indicates resistance in the wiring.  However, it should still run.  If the voltage at the coil drops below 10V, that runs the risk of not having enough to start the car though

 

Or this:

 

Ign On, Not Cranking:

Batt: 12.1V

Coil (+): 12.0V

 

 

Ign ON, Cranking:

 

Batt: 10.7V

Coil: 8.2V

 

This would indicate that your starter solenoid circuit is sharing the ignition circuit, and is overloading it.  Datsuns aren't wired that way- the START circuit is separately fused, but I've seen rewire jobs that moved it.  The idea being that you couldn't crank it of the ignition was off, like when adding a remote start.  The problem is the ignition circuit on Datsuns isn't beefy enough to handle the combined IGN/Start circuits, which is why they're split.

[AceOfDiamonds0]

Ok that might be my issue then because the voltage across my battery is 12.4V and its a new battery

 

I'll clean the connections on the starter just to be sure.

 

What gauge wire do you suppose should be going to the coil?