12v WHILE CRANKING source.

[510revisited]

I'm at the end of my efi install. Holley sniper 2300 efi. Just wiring now. Everything else is done. I'm having a hard time locating a 12v cranking source. Instructions say 12v while cranking and run position.. need help. 69 datsun 510 2 door. Stock harness. I've tried every wire that comes out of the key ignition plug. None of them stay at 12v while cranking. They all jump down to 9 ish. Btw, instructions say not to connect to starter solenoid or ign coil.

Edited December 8, 2019 by 510revisited

[Ranman72]

12 volts should only drop to maybe 11/11.5 while cranking and should work for what you are needing

how strong is your battery ?

try jumping and check cranking voltage or try installing another battery and see if it keeps closer to 12V 

im no expert so this is what i would try if it was mine 

[alfa7kar]

you could always run a relay that is triggered by the ignition and could stay constant or swithed as needed.  

[banzai510(hainz)]

The battery is going to drop less than 12 volts during cranking as the starter is draining it and the battery is in parrallel with all circuits so that’s the way it is. Adding a relay only triggers better if you have a low voltage drop across a key switch but during start the battery is draining with the starter motor so I don’t know if that really solves anything beside adding more crap under the hood.you have a hot start wire just find it it’s by the coil and ballast.The Haynes manual should have it page 181 if I remember right

 

I posted most info on you other thread but the specs says it works from 4 to 15 volts 

Edited December 8, 2019 by banzai510(hainz)

[datzenmike]

9 hours ago, 510revisited said:

I'm at the end of my efi install. Holley sniper 2300 efi. Just wiring now. Everything else is done. I'm having a hard time locating a 12v cranking source. Instructions say 12v while cranking and run position.. need help. 69 datsun 510 2 door. Stock harness. I've tried every wire that comes out of the key ignition plug. None of them stay at 12v while cranking. They all jump down to 9 ish. Btw, instructions say not to connect to starter solenoid or ign coil.

 

Did your car have an idle cut solenoid???? I think it might. This is a 12 v source that has to be on with the ignition AND while cranking.

 

The only other thing IS the ignition switch power to the distributor. The start signal is separate and only on in the start position. You don't want to tie into this or the starter won't shut off. The ignition ON position is also On  in the start position. This is the only place to connect to and far enough away from the on/off/on/off draw of the coil. I think they are worried that the distributor will cause a lumpy 12v source. The ignition switch is as far away from the distributor, and as close to the battery as you can get other than a relay.

[510revisited]

1 hour ago, datzenmike said:

 

Did your car have an idle cut solenoid???? I think it might. This is a 12 v source that has to be on with the ignition AND while cranking.

 

The only other thing IS the ignition switch power to the distributor. The start signal is separate and only on in the start position. You don't want to tie into this or the starter won't shut off. The ignition ON position is also On  in the start position. This is the only place to connect to and far enough away from the on/off/on/off draw of the coil. I think they are worried that the distributor will cause a lumpy 12v source. The ignition switch is as far away from the distributor, and as close to the battery as you can get other than a relay.

There he is! I knew mike would jump in.... I tested all the wires coming out of the back of the ignition switch. None stayed at 12v while cranking. I will test again, as I was in a bit of a rush cause it was getting late. How exactly would one run a new relay mike. I'm no electrician..

I dont know if it had/has the idle cut solenoid

Edited December 8, 2019 by 510revisited

[john510]

What Hainz said.

[banzai510(hainz)]

69 never had a idle cut off.maybe the 72 and later had them.

ok like I said look in the Haynes manual which you should have one or a print out of the schematic somewhere.

you have a hot start wire.Its there.pull the starter wire off the starter.Now you can put the key in Start while you have one side of the meter on ground and the other on the wire you think it is.Im don’t know a 69 Wiring but should be close to the wire colors I said previously .This is simple.Find the black white wireThis will have 12v with key On.Black blue with key in start.If you can’t figure this out stick with a carb but you’ll still need it to run the point ignition or a Pertronix conversion with a ballast resistor unless you get a matchbox but I would think you need to short the black while wire with the black blue.

If you can find the black green wire which hooked up to the ballast resistor this will be shorted to the black blue. .the black blue has a cheesy C crimp copper contact that shorts the wire.
maybe you can get your money back

[Crashtd420]

12 hours ago, 510revisited said:

I'm at the end of my efi install. Holley sniper 2300 efi. Just wiring now. Everything else is done. I'm having a hard time locating a 12v cranking source. Instructions say 12v while cranking and run position.. need help. 69 datsun 510 2 door. Stock harness. I've tried every wire that comes out of the key ignition plug. None of them stay at 12v while cranking. They all jump down to 9 ish. Btw, instructions say not to connect to starter solenoid or ign coil.

I think your reading this wrong....

12volt while cranking and run just means ignition nothing more.....

 

And it will drop while cranking because of the current the starter needs.....

 

 

[banzai510(hainz)]

This is not a trick question.Heres my answer
12 v On. Blackwhite wire

12v Start Black/blue or Blackgreen. Now go by there instructions.So I’m not sure NOW if you really want to short them together cause if you put the key to On you won’t get the trigger cause it’s on already you need that 12v trigger to go somewhere.

 

check your other thread to many pages now to find.mite get confusing for you and us.

 

Crash has his done best to get he’s wiring hookup

[Crashtd420]

He doesnt need a start signal....

 

He needs ignition.....

 

All they are saying is dont use an accessory wire that shuts off while cranking..... 

[510revisited]

16 minutes ago, Crashtd420 said:

He doesnt need a start signal....

 

He needs ignition.....

 

All they are saying is dont use an accessory wire that shuts off while cranking..... 

EXACTLY. I tried the blue wire that goes to the coil. It drops to 9 ish as well.

[Crashtd420]

Even if you check at the battery it's going to drop..... 

I really think your over thinking this....

Just looked at the wiring for the sniper unit .... and it really only needs 4 wires hooked up...

where does it even ask for a start signal?

Use the basic wiring picture....

The crank signal is going to a Holley distributor... you dont need those wires for your setup...

[banzai510(hainz)]

I said disconnected the starter wire to the selinoid so you not loading down the battery and then check the wire for 12volts when key goes to start .

[banzai510(hainz)]

Like I said fine the On wire blackwhite

Start wire black blue/Blackgreen

 

put a extension wire to the length you need in those 2 connectors and route them to where you need going by the drawing Crash posted on other thread 

[john510]

There will be NO "12 volts while cranking"  anywhere on that car while engaging the starter.

[datzenmike]

4 hours ago, 510revisited said:

There he is! I knew mike would jump in.... I tested all the wires coming out of the back of the ignition switch. None stayed at 12v while cranking. I will test again, as I was in a bit of a rush cause it was getting late. How exactly would one run a new relay mike. I'm no electrician..

I dont know if it had/has the idle cut solenoid

 

Black/White is 12 volts ignition ON and START position. At same time it also powers a couple of fuses in the fuse box for radio, heater and wiper. 

Black/Blue is 12 volts only in the START position. Stay away from this. If joined to the Black/White the starter will not stop cranking!!!

 

5 minutes ago, john510 said:

There will be NO "12 volts while cranking"  anywhere on that car while engaging the starter.

 

In addition to the 12v start signal to the starter, there will be 12 volts to the coil and 12 v to the ballast resistor. If equipped with an idle cut solenoid it will also have 12v

 

[510revisited]

1 minute ago, john510 said:

There will be NO "12 volts while cranking"  anywhere on that car while engaging the starter.

I'm starting to see, believe this... I have not found any thing that comes close. Even setting up a relay. How would I make a 12v while cranking source?

[datzenmike]

 

2 hours ago, john510 said:

There will be NO "12 volts while cranking"  anywhere on that car while engaging the starter.

 

 

In addition to the 12v start signal to the starter, there will be 12 volts to the coil and 12 v to the ballast resistor. All headlights, marker lights, horn, interior light, clock and brake lights will work during start. If equipped with an idle cut solenoid it will also have 12v

[510revisited]

Mike, I've tested the black/white wire during cranking. It drops down to 9 and a half ish or so. No wire that anyone has suggested stays at 12 when I crank the car. Am I measuring wrong. 20v setting on my voltmeter. Red to wire, ground to body... 

1 hour ago, datzenmike said:

In addition to the 12v start signal to the starter, there will be 12 volts to the coil and 12 v to the ballast resistor. All headlights, marker lights, horn, interior light, clock and brake lights will work during start. If equipped with an idle cut solenoid it will also have 12v

 

 

[datzenmike]

Well try measuring across the battery posts while cranking. You have to expect the starter load to drop the voltage somewhat.

[john510]

10 minutes ago, datzenmike said:

Well try measuring across the battery posts while cranking. You have to expect the starter load to drop the voltage somewhat.

That's my point.

[datzenmike]

Ahhhhh.

[john510]

15 minutes ago, 510revisited said:

Mike, I've tested the black/white wire during cranking. It drops down to 9 and a half ish or so. No wire that anyone has suggested stays at 12 when I crank the car. Am I measuring wrong. 20v setting on my voltmeter. Red to wire, ground to body... 

 

No you're not measuring wrong.What is it you have to have 12 volts for while cranking the starter ? A brand new battery won't show 12 volts when you hit the starter.That's normal.

[thisismatt]

Maybe connect to another car's battery while you're cranking yours?