73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Scott Wayne on July 20, 2021, 03:47:23 PM
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Hey y’all I just bought a 83 C20 and it’s got an edelbrock 1406 carb with an electric choke. I didn’t realize until I had already had it a few days that the choke doesn’t have power hooked up. I’ve been doing research on where to get power from, some people suggested the oil pressure switch but I don’t see one installed. There’s an opening in the fuse panel in the cab labeled “choke” but there are no female tabs to hold a fuse.
So basically my question is how else can I safely get power to the choke?
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Connect the choke heater wire to one of the IGN cavities in the fusebox through a 2-prong non-grounding oil pressure switch (OPS). The OPS (image) can be threaded into one of the engine oil galley ports either at the back of the intake manifold next to the distributor or down adjacent to the oil filter. The OPS ensures that the choke doesn't open up with the ignition switched ON unless the engine is running too.
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I don’t believe this is a stock intake manifold but I’ll post two pictures. Second is a thread hole above the oil filter, is that for an oil pressure switch? Sorry I’m so new to this.
https://imgur.com/a/DnfQ7PN
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Another thought I had was to use an “add a circuit” wire on a 12v keyed ignition fuse that’s already in the panel, as I have no empty slots for a new circuit. Could this work?
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He's not saying in the intake manifold, he's saying behind it, near the distributor.
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He's not saying in the intake manifold, he's saying behind it, near the distributor.
This ^^^^^, but it appears there is an oil pressure gauge sender occupying that location already. To plumb the OPS and gauge sender to share the same galley would require a tee fitting and ~2" x 1/8" NPT nipple. The oil galley tap down near the oil filter should be 1/4" NPT and located just forward from the filter - not the threaded hole that you pictured above the filter.
Post a clear, full-frame pic of the fusebox.
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Thank you for the help with this, I don’t really know anyone that can help me so I have to rely on what I can find on the internet.
https://imgur.com/a/MRsn2bL
That’s the best pic I could get with the brake assist thing in the way
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Use either of the two ignition power taps pictured. Both are protected by the 20-amp fuse positioned directly below them.
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Thank you bd!! I’ll get started on this ASAP!
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If you want the power wire to integrate nicely with the factory fusebox connector and lock in place, pick up an American Autowire 500429 (https://www.summitracing.com/parts/aww-500429) ATO power tap kit. You can also acquire a Standard Motor Products S-939 (https://www.summitracing.com/parts/smp-s939) molded connector for the OPS if you like. Neither are necessary but they make for a cleaner installation.
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I thought I could go straight from the fuse box to the choke without an OPS?
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You could, BUT THEN the choke would begin to open as soon as the ignition is switched on. Suppose it is icy weather. You switch the ignition on and crank the engine to start. It doesn't start right away, so you crank the engine repeatedly. Finally, the engine fires but then dies almost immediately. You crank it some more and it starts but you find that it is a struggle to keep it running and it backfires through the carburetor. Why? Because the whole time you were cranking the engine, from the moment you switched the ignition on, the choke was heating up and opening. By the time the engine started the choke was fully open, so the engine wasn't getting sufficient fuel to run efficiently. Had you installed the OPS, the choke wouldn't begin to open until after the engine was running.
Essentially, installing a choke OPS provides improved cold weather starting and drivability. It is in your best interest.
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Then I’m back to square one because I don’t have an OPS
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https://imgur.com/a/MMiNdGy
Here’s a better pic, there is no hole forward of the oil filter, just the freeze plug.
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Looks like some engine degreaser will help ;D
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GM original P/N 14034354 with 1/4" NPT threads crosses to Standard Motor Products PS144 (https://www.rockauto.com/en/parts/standard+motor+products,PS144,oil+pressure+sender+/+switch,4588), et al.
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You could, BUT THEN the choke would begin to open as soon as the ignition is switched on.
I checked the two ignition power taps and they both have power without the key in the ignition. So that would mean that the choke would always have power if I were to wire it directly, correct? But if I’m not mistaken I want a 12v keyed ignition source?
I live in Texas so I’m not really concerned with cold starts. If I have to press the gas a little in the winter and let it warm up longer before I leave then I’m fine with that.
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As you wish.
(http://forum.73-87chevytrucks.com/smforum/index.php?action=dlattach;topic=38777.0;attach=53421;image)
Those two power taps testing hot at all times is interesting. The two taps directly above the 20-amp IGN fuse located along the left margin of the fusebox and the one tap directly below it, all three connected to pink or pink/black wires, should measure 12 volts only with the ignition key in the start and run positions. Do the turn signals work without the key in the ignition?
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I apologize if I’m coming across as difficult or that I don’t appreciate your help, because I do, it’s just frustrating because this is my daily driver and I’m fairly new to this. So thank you for your help with this, I really do appreciate it.
I would go through an OPS switch I just don’t see anywhere to put it. I’ve looked all around the oil filter and the only hole that looks like a 1/4 NPT is the one I sent a picture of earlier, above the filter. If that’s not it then I don’t see where else it could be.
I think I spoke too soon when I said they have power. I checked with a test light and there is continuity, but then I just checked again with a multimeter and they only have power with the key on. The turn signals don’t work without the key in the ignition.
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Look closely at this prior reply and image posted by VileZambonie...
Looks like some engine degreaser will help ;D
(http://forum.73-87chevytrucks.com/smforum/index.php?action=dlattach;topic=38777.0;attach=53423;image)
Camouflaged beneath all that caked on gunk within the orange circle hides a 1/4" NPT plug. Clean the vicinity of the plug, install the switch linked in Reply #15 using a smear of Teflon pipe dope on the threads, and string the wire tapping ignition power per Reply #7. Viola!! The job is done with a properly functioning choke! All the information you need, including linked parts, is in this thread.
Replacing the valve cover gaskets might be prudent, too. ;)
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Oh my goodness *face palm*
Ok but in my defense that plug is in the first picture too! Lol
Thank you guys, I’m going to order those parts and get it wired up proper.
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I have a simple question, was your truck not originally equipped with an electric choke? My 1981 C10 was, and if you could find that wire couldn’t you use that? Maybe give a wiring diagram a good look and see if there was one it would be on the diagram and it would tell you what color the wire is, then you could look for a disconnected wire that color near the carburetor??
Just a suggestion.
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I have a simple question, was your truck not originally equipped with an electric choke? My 1981 C10 was, and if you could find that wire couldn’t you use that? Maybe give a wiring diagram a good look and see if there was one it would be on the diagram and it would tell you what color the wire is, then you could look for a disconnected wire that color near the carburetor??
Just a suggestion.
Likely the problem has been solved, but just for discussion, IF the truck originally came with an electric choke (and i don't see why it wouldn't, unless originally diesel....?), then there should also be a plug going to the oil pressure switch----which i think senses oil pressure to allow power to the choke etc.?
IF the OP elects not to use an OPS, then this plug, if present, would have to be "jumpered," so that power always goes to the choke when key is on.
i had to do it this way: As you may know i switched from v-8 to v-6. 4.3 v-6's do it a little different with the OPS: It's in roughly the same spot, but it's a different size and not compatible with my original v-8 plug. i haven't had any cold starting problems.
P.S. If the truck DID originally come with an elec choke, then i think the wire should be green.