12v Electric Choke Wire Help

[FormerBigDaddy]

Hello all,

I'm currently ready to upgrade to a 3g alternator on my truck (84 f350 460 auto). I have everything I need ready to go on that but I need help figuring out how to wire up my 12v choke from my edelbrock 1406. I didn't realize until now, that the PO owner had the electric choke wired to the 1G alternator as if it were a stock carb. I have since learned that the stator is only 7v and not enough for my carb. I understand it CAN be done but i'd rather do it right while I'm messing with the wiring. I know i SOUND like i know what I'm doing here but i really don't. I only know from what i've read and seen in pictures and videos and I couldn't tell you where to locate a proper 12v source or even what a 12v source is. I don't know the first thing about relays, switches, etc.

Thanks in advance!

[Gary Lewis]

Chris - Thanks for joining. We can help you through this, and it is probably something that needs to be on our 3G page, so we will want to do it "well".

However, as said in the FB chat, I'm headed out right now and won't get to this until either late today or tomorrow. Perhaps the others will help in the interim.

Having said that, please go to the New Members Start Here folder, read the guidelines, and then start a new thread about yourself and your truck. The guidelines are important as we hold everyone to them. And, don't forget the signature thing as that helps us answer questions w/o having to scroll back through everything trying to figure out what you have. Instructions for a signature on on the FAQ's page: Bullnose Forum/FAQ's in the menu.

[85lebaront2]

I will reply to that one. The 351W used a 12V electric choke operated via a relay from the alternator, but there is an easier solution, first does your truck have the electric in-tank pumps? If it does you are halfway there, if not, go to a parts store and buy an oil pressure switch for a 1987 Horizon 2.2L, it will have 3 terminals on it. The 2 outer ones (parallel to each other) are normally open, and close with oil pressure. This will provide you with an engine running closed switch. Use a 12V source, if you come off the alternator or battery use an in-line fuse, probably 20 amp, so if something shorts you won't have a fire. Chrysler used these for oil pressure light and choke power.

[FormerBigDaddy]

I will reply to that one. The 351W used a 12V electric choke operated via a relay from the alternator, but there is an easier solution, first does your truck have the electric in-tank pumps? If it does you are halfway there, if not, go to a parts store and buy an oil pressure switch for a 1987 Horizon 2.2L, it will have 3 terminals on it. The 2 outer ones (parallel to each other) are normally open, and close with oil pressure. This will provide you with an engine running closed switch. Use a 12V source, if you come off the alternator or battery use an in-line fuse, probably 20 amp, so if something shorts you won't have a fire. Chrysler used these for oil pressure light and choke power.

I do have an in tank electric fuel pump. But the PO made modifications to the fuel systems and I’m pretty certain it wasn’t originally that way.

Unfortunately I don’t understand much else of what you said. I much appreciate the reply but gonna have to get more basic with me. I don’t know what 12v sources even are or where to find them.

[Gary Lewis]

I do have an in tank electric fuel pump. But the PO made modifications to the fuel systems and I’m pretty certain it wasn’t originally that way.

Unfortunately I don’t understand much else of what you said. I much appreciate the reply but gonna have to get more basic with me. I don’t know what 12v sources even are or where to find them.

Ok, let me see if I can help. What Bill suggested is brilliant, and that's exactly why we have a forum - someone has an idea and someone else has a better one.

The drawing below shows your fuel pump control circuit. In the upper left you'll see "Hot In Start or Run", and below that a red wire with a yellow hash mark (R/Y H) that goes from Fuse 18 to the Oil Pressure Switch. That means that when the key is either in Start or Run there is power provided to the oil pressure switch via the fuse and that wire.

As shown the switch is "open", meaning there's no connection between the terminal on the top and the one on the bottom. But there's a note that says "Closed with engine running", and that means that battery voltage will flow across the switch to the Fuel Pump Cutoff Relay when the engine is running. And that will close the contacts on that relay and power the fuel pump.

But, I've drawn a red arrow and added "Choke". If you tap into the red/yellow hash wire after the oil pressure switch you can run that wire directly to the choke and it will get battery voltage when the engine is running, and only when the engine is running.

So, where are these components? The oil pressure switch is on the back of the engine, right in front of the firewall and behind the carb. If you need I can get pics of the one from Big Blue, but you should be able to find it easily, and it'll have two wires to it, and both are R/Y H.

So, which one do you tap into? The one that goes to the fuel pump cutoff relay, and it is between the master cylinder and the driver's fender on the firewall. I've put an illustration below that shows what it looks like.

So, are you ok with doing that wiring? Do you need suggestions on how to do that? (Please don't tell me you are going to use an insulation displacement connector to tap into the R/Y H wire and are going to use a cheap wire crimper to crimp the terminals. )

[myrl883]

Ok, let me see if I can help. What Bill suggested is brilliant, and that's exactly why we have a forum - someone has an idea and someone else has a better one.

The drawing below shows your fuel pump control circuit. In the upper left you'll see "Hot In Start or Run", and below that a red wire with a yellow hash mark (R/Y H) that goes from Fuse 18 to the Oil Pressure Switch. That means that when the key is either in Start or Run there is power provided to the oil pressure switch via the fuse and that wire.

As shown the switch is "open", meaning there's no connection between the terminal on the top and the one on the bottom. But there's a note that says "Closed with engine running", and that means that battery voltage will flow across the switch to the Fuel Pump Cutoff Relay when the engine is running. And that will close the contacts on that relay and power the fuel pump.

But, I've drawn a red arrow and added "Choke". If you tap into the red/yellow hash wire after the oil pressure switch you can run that wire directly to the choke and it will get battery voltage when the engine is running, and only when the engine is running.

So, where are these components? The oil pressure switch is on the back of the engine, right in front of the firewall and behind the carb. If you need I can get pics of the one from Big Blue, but you should be able to find it easily, and it'll have two wires to it, and both are R/Y H.

So, which one do you tap into? The one that goes to the fuel pump cutoff relay, and it is between the master cylinder and the driver's fender on the firewall. I've put an illustration below that shows what it looks like.

So, are you ok with doing that wiring? Do you need suggestions on how to do that? (Please don't tell me you are going to use an insulation displacement connector to tap into the R/Y H wire and are going to use a cheap wire crimper to crimp the terminals. )

Ford used a 3 terminal oil pressure sender just like Chrysler... It was commonly used to turn the electric fuel pumps on 460 trucks off if oil pressure was lost. I think the easiest would to be to use one as suggested above, or wire in a relay to control power to the choke. If you use a Bosch style relay, 7 volts is enough to hold the coil in. Use the stator wire on the control side of the relay, then use the load side of the relay to power your choke.

However you wire it, make sure you only have power in RUN, and not ACC!

[Rembrant]

I know there's already lots of great info posted here, but I was just going to add that you could buy one of the smart relays like the Rostra one here listed below:

https://www.ebay.com/itm/Rostra-250-2951-SourcePWR-Plus-12V-7-5-Amp-Intelligent-Accessory-Power-Supply/123077949915?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I am currently running my Holley choke with the Ford factory wire from my 1G alternator, and it seems to work OK. The only reason I did this was after some reading online I found a lot of people that had done the very same thing with Holley carbs on Fords going back decades. However, I do remember reading that the Edelbrock carb chokes don't like the lower 7vdc supply?

In any case, yes, I know it is not correct this way, but if I ever do get around to changing it, I was just going to use one of these relays so it could be a stand alone circuit.

[Gary Lewis]

I know there's already lots of great info posted here, but I was just going to add that you could buy one of the smart relays like the Rostra one here listed below:

https://www.ebay.com/itm/Rostra-250-2951-SourcePWR-Plus-12V-7-5-Amp-Intelligent-Accessory-Power-Supply/123077949915?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I am currently running my Holley choke with the Ford factory wire from my 1G alternator, and it seems to work OK. The only reason I did this was after some reading online I found a lot of people that had done the very same thing with Holley carbs on Fords going back decades. However, I do remember reading that the Edelbrock carb chokes don't like the lower 7vdc supply?

In any case, yes, I know it is not correct this way, but if I ever do get around to changing it, I was just going to use one of these relays so it could be a stand alone circuit.

That's interesting, Cory. Apparently it senses the voltage increase when the alternator kicks in and then closes its internal relay.

However, in the video on their site I dislike the way they run long wires from the battery through the firewall without a fuse. I think that is poor practice.

[Rembrant]

That's interesting, Cory. Apparently it senses the voltage increase when the alternator kicks in and then closes its internal relay.

Yes, that is my understanding of it. I have it on my to-do list for down the road. The carburetor choke was my first thought for it, but I could also use it as a trigger for other devices so that I don't have to go digging through my wiring harness to get an ignition on/run signal.

 

[Gary Lewis]

That's interesting, Cory. Apparently it senses the voltage increase when the alternator kicks in and then closes its internal relay.

Yes, that is my understanding of it. I have it on my to-do list for down the road. The carburetor choke was my first thought for it, but I could also use it as a trigger for other devices so that I don't have to go digging through my wiring harness to get an ignition on/run signal.

That should work, but with the minor problem of those accessories not coming on when the alternator fails. But then that would also be the case if you used the stator wire to pull in a relay, which I've done frequently.

I guess I was just put off by several things about that unit. First, they don't tell you how it works. Then they say it "illuminates the fuse". What? Maybe that is because they speak both English and Chinese, and their English is far superior to my Chinese. And last, they show using no fuse and, to top it off, use a cheap crimper for the connections.

So maybe I shouldn't penalize the product with the way they present it? The product itself seems like it would solve a lot of problems.