Sniper Switched 12V Source from Voltage Regulator

[MIDEVIL214]

I'm in search of a more reliable switched 12V source for my Sniper EFI. It needs to be "clean source" that is hot in run and crank. Wasn't one of the original voltage regulator wires a good source? I have the seabiscuit diagrams which show yellow, green/red, orange, and black/red. I removed the regulator but the source wires are still there at the firewall (1974). I have a one wire 3g alternator so the wires from the regulator to the engine have been removed also.

The starter motor relay terminal was my original sniper switched 12v source and the vehicle has been running well using it. My problem is the sniper ecu and handheld are losing power when the motor dies. I was told the hand held and ecu should still be powered up even after a stall or failed cold start if the key position wasn't changed. Isolating a better 12v source is my first task and should help the data log process.

 

[Broncobowsher]

Good source that bypasses the original ballast resistor. Sometimes hot in start position, but not always. Originally there was no need for a post to be hot in both, the ignition bypass (I post on solenoid) took care of that. I did a starter solenoid delete once when I did a mini starter with the solenoid built in. Sometimes in start, it wouldn't start. Even changed the ignition switch to try and fix it. For me it was easy, the gauges were wired to the run position of the ignition switch. If during start I see the gauges drop off, no start. If the gauges stay alive during start, the ignition and EFI had power and it should start.

Not sure what you are doing for ignition. But if you don't need the ballast resistor anymore, add a wire from the I post on the solenoid to the power to the regulator you want to use to power the EFI. That way you will have power in both start and run positions.

And soon enough someone will step in and say that is not needed, they have been running off the ignition and it always has power during start. They got lucky. I almost (but not always) had run power during start. And a different ignition switch that did the same thing says to me that some people get luckier than others.

And if the controller shuts off the same moment the engine stalls, that is because the EFI lost run power. As far as the EFI sees it, looks just like you turned off the ignition switch. Loss of power is a loss of power. Weather it be from turning off the ignition switch or from bad wiring, it will just turn off. The displaying blacking out tells you that.

 

[MIDEVIL214]

Good source that bypasses the original ballast resistor. Sometimes hot in start position, but not always. Originally there was no need for a post to be hot in both, the ignition bypass (I post on solenoid) took care of that. I did a starter solenoid delete once when I did a mini starter with the solenoid built in. Sometimes in start, it wouldn't start. Even changed the ignition switch to try and fix it. For me it was easy, the gauges were wired to the run position of the ignition switch. If during start I see the gauges drop off, no start. If the gauges stay alive during start, the ignition and EFI had power and it should start.

Not sure what you are doing for ignition. But if you don't need the ballast resistor anymore, add a wire from the I post on the solenoid to the power to the regulator you want to use to power the EFI. That way you will have power in both start and run positions.

And soon enough someone will step in and say that is not needed, they have been running off the ignition and it always has power during start. They got lucky. I almost (but not always) had run power during start. And a different ignition switch that did the same thing says to me that some people get luckier than others.

And if the controller shuts off the same moment the engine stalls, that is because the EFI lost run power. As far as the EFI sees it, looks just like you turned off the ignition switch. Loss of power is a loss of power. Weather it be from turning off the ignition switch or from bad wiring, it will just turn off. The displaying blacking out tells you that.

I'm running a DUI distributor for my ignition. They recommended a sole/clean signal for the sniper switched 12v source. I have a few other items on that terminal for switched 12v so it's not exactly clean. It's the switched source for the DUI and a switched source for my S3 switch pod, and the sniper. OE Brown wire too.

 

[DirtDonk]

Yes, the old Green w/red wire from the regulator is normally a good source.
With a volt-meter, verify that it's got 12v while in ON and START. Simple to check...

Using the old "I" post with the old Brown wire still there (original wiring??) is only good part of the time. When the key is on initially, it might see a full 12v from the ignition switch. But being at the far end of the resistor wire means that at most times it's lucky to have 9v and might even be as low as 5v or 6v if your resistor wire is getting old.
The way I understand modern electronics (not very well mind you) that low voltage might be insufficient for the ECU to do it's thing. That might be part of your shutting off issue as well.

As was said, the Green w/red wire might not always have power in START because the ignition switch is either old and tired, or is a newer purely defective unit supplied from overseas. However, from the factory it's supposed to have power in ON and START, and no power while in ACC.
So you can use the Green w/red wire, but maybe still tie into the Brown wire at the starter relay as your backup in case your ignition switch is not doing it's job.
It might still not be the best spot, due to the resistor wire, but you can get around that in different ways too.

How is your DUI connected to 12v now? A relay, or a bypass wire perhaps?

 

[hyghlndr]

I used the wire to the electric choke, is hot in crank and run.

 

[MIDEVIL214]

Yes, the old Green w/red wire from the regulator is normally a good source.
With a volt-meter, verify that it's got 12v while in ON and START. Simple to check...

Using the old "I" post with the old Brown wire still there (original wiring??) is only good part of the time. When the key is on initially, it might see a full 12v from the ignition switch. But being at the far end of the resistor wire means that at most times it's lucky to have 9v and might even be as low as 5v or 6v if your resistor wire is getting old.
The way I understand modern electronics (not very well mind you) that low voltage might be insufficient for the ECU to do it's thing. That might be part of your shutting off issue as well.

As was said, the Green w/red wire might not always have power in START because the ignition switch is either old and tired, or is a newer purely defective unit supplied from overseas. However, from the factory it's supposed to have power in ON and START, and no power while in ACC.
So you can use the Green w/red wire, but maybe still tie into the Brown wire at the starter relay as your backup in case your ignition switch is not doing it's job.
It might still not be the best spot, due to the resistor wire, but you can get around that in different ways too.

How is your DUI connected to 12v now? A relay, or a bypass wire perhaps?

Thanks as usual Paul. I ended up adding a relay for the switched source. I used the I terminal for my trigger wire (85), wire to battery (30), wire to ground (86), and pink wire to sniper (87).

The DUI is actually running off the I post. Is that a no-no?

 

[DirtDonk]

Sort of. Depends on how everything else is wired. Is there still another wire from the ignition coil on the same terminal?
And if so, is this original wiring from Ford? Or is it fully rewired?

If it’s already been running, then I assume there is still a wire other than a D.U.I. wire on the same terminal. If it’s the original brown wire with the original harness, then no, it’s not really the optimal place to run your ignition from.

 

[MIDEVIL214]

Yes, original brown Ford wire is still at that terminal. The DUI is connected to that terminal and I'm also using it as a switched 12v source for and S-spod relay/fuse box that powers switches for an ARB air compressor, locker switches and some off-road LEDs. The second DUI wire ties directly into the sniper system. As mentioned, I'm also using that terminal now to trigger a relay for the sniper efi switched 12V source.

Is it not ideal for the DUI due to wire gauge or it being a dirty source? I can add another relay in similar fashion to the sniper trigger.

 

[DirtDonk]

Probably not.
For one reason it sounds like there are too many things on the one circuit. It should probably just be used to trigger a relay or three, and those used to power other accessories.
For the other reason is that you’re probably not getting 12V all the time.
That’s at the business end of your resistor wire so might be lower voltage than you need to power some of these things at their optimum level.

Easy enough to test though.
After it’s been running for a few minutes you should measure the voltage at the “I” terminal. If it’s still system voltage when the engine is running (approx. 14v), then you’re probably OK.
But it still sounds like too many items that need good power for that one circuit.