Electric choke hookup?
 

I've been reading up on where exactly to hook up the positive wire for my electric choke, but I haven't been able to find a conclusive answer that works for me.

I've read that it should be hooked up to a hot in RUN wire, not a hot in START, and not an always hot, but I've seen all sorts of different opinions on which hot in RUN source to hook to. Some say alternator output, but that's AC, and I don't need another "results may vary" setup in my equation right now, some say the S terminal on the starter solenoid, but I don't have any current to that with the key in the RUN position (is that normal?), and some say the I starter solenoid terminal, but I only have 7 volts to that in RUN (is that normal?).

I'm finally making progress again, but I need some input from some of the electrical guys out there.

Thanks, AleX

Do you actually have the truck running when you did these readings? But that 7 volts def sounds off to me. I'm interested in finding a good spot to hook to as well.

All my wiring diagrams show the electric choke connected to the alternator "S" terminal.

The factory choke gets hooked to the "S" terminal of the alternator. The output of this terminal is AC. If you try to get a voltage reading using the DC scale of your VOM it'll read something like six or seven volts.
This is fine for the original factory carb. it was designed to run with this voltage, however, if its an aftermarket carb, the choke on these is designed to run w/ 12v DC.
Find a circuit that is hot in run position and tap into that circuit.
Also, the "S" terminal of the starter solenoid is only hot in the start position, the "I" terminal on the solenoid is also only hot in the start position. Don't hook the choke to either of these wires. It will only recieve power for a few seconds while the starter is turning over.
Some have hooked aftermarket carbs to the factory wiring with success but there is no solid information on how this affects the choke operation.

Edge, no the engine is not running, the key is only in the run position. I would love to be able to give you some readings with the engine actually running, but that still isn't happening.....

Fabman, I was referring to the S terminal on the solenoid, not the alternator.

Mike, this is an aftermarket carb, Holley 4bbl, and thanks for the info on the I and S. That makes me wonder a little bit though, since the I terminal has about 7 volts when the key is on start. Could I have some wiring backwards on the alternator?

I just hooked the choke up to the most central terminal on the alternator as I read some people do, with unknown success as you sayd Mike, and my choke is operating from that, but I'm not sure if it working right.

Finally, after cranking for a looooong time without the engine starting, my coil is hot, is that a bad sign? I've never noticed it as warm before, but I've never really checked, is it always warm, or is that a sign of a failing coil?

AleX

The choke needs to be powered the entire time the engine is running. The factory setup had it connected to the stator (S) terminal of the alternator, since it's only hot when the engine is actually turning and the alternator is online. As Mike said, it's an AC signal and looking at it with a run-of-the-mill multimeter set to DC is not useful information.

I have an Edelbrock carburetor and it calls for 12 volts to the choke, so I connected it to what used to power the idle stop solenoid (which went away with the original carburetor). On my '79, it's protected by a fuse in the fuse panel. This has worked out great; however you need to be careful not to leave the key in RUN without the engine actually running.

It shouldn't hurt anything to connect your Holley's choke to the same stator terminal of the alternator, but you'd need to watch it warm up to make sure that the choke is opening as quickly as you'd like. The actual RMS level of the stator terminal is lower than 12 volts, so it most likely will not heat up as quickly, and take longer to open. All a choke is is a bimetallic strip that unwinds as it gets hot; it takes current through it to make that happen. The factory electric choke setup was only meant as an assist to help it open faster - it was never built as a stand-alone setup to the best of my knowledge. It was always used in conjunction with a hot-air stove setup. As such, you really should be connecting your aftermarket choke to 12 volts hot-in-RUN like I have so that it behaves as expected. That's one less variable in the equation.

One final note, Mike already covered it, but don't hook the choke up to any post on the starter solenoid.

I'm not sure how hot the coil is supposed to get. Anything bolted to a running engine is going to be hot to the touch, but I haven't felt it under the condition of cranking without the engine starting. An ignition coil pulls a significant amount of current (the primary winding is only an ohm or so) but the current is not continuous if the ignition module is powered and is receiving a trigger signal from the distributor pickup. To make sure this is happening, you can connect a test light from the TACH TEST (negative) coil terminal to clean, unpainted metal on the engine (ground). As you crank the engine over from the cab, you should see the light BLINK as the ignition module continuously grounds and open-circuits the coil to fire the plugs.

I have always used the Stator terminal on electric chokes on Fords. The reason is there is no voltage present at that point until the alternator starts turning. If you leave the key on the choke will not begin to open. The element in the choke does not care if it is supplied AC or DC. My 78 has used a Holley for nearly 20 years, starting hot or cold has never been an issue. Many AMC and GM products used DC voltage to power chokes using a set of contacts in the oil pressure sender, basically for the same reason. Don

I just hooked a new Holley electric choke up on my truck. Seems to work correctly. I plugged it in where the original Motorcraft carb was hooked up. This is on a 79 F150. It's the black/white wire I plugged into. It runs through the harness down to the alternator. I think hooked to S.

https://www.ford-trucks.com/forums/p...ictureid=54785

I know this is a little old but exactly what I was looking for, thanks for the info. Great pic and nice looking engine 73 fourxfour.
Charlie

if you have the holley 4160c make sure the vac line is hooked up because this keeps air flow thru the choke so it has a longer life,atleast thats what my book said

did some reading up on the choke hook up elect. It's on a wire that is connected to the oil guage---choke will not open if there is no oil pressure. Engine running=oil pressure up=elect to the choke. Not sure where the connection is. But I've had this problem for a while. It's working just fine now. 1985 Ford E-150 351 Win w/4v carb.

This thread is almost 2 years old. I don't understand what you're saying; are you asking a question or making a statement? You are incorrect in your assertion that the choke is connected to the oil sending unit. The sending unit gives a ground-out signal and cannot supply power. In post #6, I clearly explained that the factory electric assist choke pulls power from the stator terminal of the alternator; aftermarket applications often require a hot-in-RUN 12-volt source. Note that this forum covers 73-79 pickups, not 80's Econoline.

The thread might be 2 yrs old but I just had the problem last week and read it. I said I didn't know how the elec hook up worked or where it was---maybe the reapir manual I'd been reading is wrong.
There is also someone else that agrees with me on -it has to do with the oil pressure.
I was just stating what I had read in my manual so as to maybe help someone else
If I have a question I will ask a question--to clear up any confusion.
This van is all original--wiring and all.

Maybe your thinking of Chevys? I think they used an oil pressure switch to send power to the electric choke. That's how I hooked up mine on my 79 f150. Just picked up a normally open oil pressure switch with 1/8npt threads and a 1/8 npt tee. Ran fused battery power to the switch and then to the choke. Works great and only sends power to the choke when the engine is running.

OK-here is where I got my information.
As I stated-it's a 1985 Ford E-150
I've had it since 1987.
The manual is-CLYMER SUPER Shop Manual. FORD 2-WHEEL DRIVE FULL-SIZE..F-series Pickups and Econoline Vans*1969-1987
On the binding it has at the bottom--T880 (guess that's the manual number).
On page 369 in the right hand columnit reads--copied from the manual.
"OIL PRESSURE
INDICATOR SWITCH"
"A molded connector and 3 terminal oil pressure switch are used with engines equipped with an electric choke heater. The open circuit in the switch prevents the heater from operating untill the engine is started and there is oil pressure. Engines without an electric choke heater use a single terminal switch."