After trying to get Patience started this evening, I started poking around the top of my engine, checking out the ignition coil (looks old) and trying to determine what the plug in the picture below is for. While I was looking at it, the whole boot popped off the carb (oops). The blue female plug (circled in yellow) is attached to a rubber boot that covers the other item circled in yellow. Originally, the wire coming off of the blue plug was soldered to the other end. What the heck is this?
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Other questions:
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<!--[if !supportLists]-->1)<!--[endif]--> How long does it take for a flooded engine to be non-flooded? In other words, how long should I wait until I try to start the beast again? How would I tell if I’ve flooded my engine?

<!--[if !supportLists]-->2)<!--[endif]--> What’s the benefit of replacing a working ignition coil? Any? The ignition coil on my 1973 F100 looks horribly old and a neighbor thinks it could be the original.

<!--[if !supportLists]-->3)<!--[endif]--> How can I tell if my choke is sticking open? Is there a pictorial anatomy of a carburetor, along with descriptions of what each part does?
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Thanks –
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Fish
1973 F100 390ci
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1)<!--[endif]--> I can tell I'm flooded when I'm smelling gas. I usually only have to wait a few minutes before I can get it going.

<!--[if !supportLists]-->2)<!--[endif]--> I can't see any benefit in replacing something that is already working? I suppose if it's old and near the breaking point but still working you could be saving yourself the trouble of replacing it once it does break... but personally I have enough crap that NEEDS replacing and I focus on that rather than replacing stuff that is working alright.

<!--[if !supportLists]-->3)<!--[endif]--> From the picture it looks like you choke is already closed. That could be a source of your flooding. If it's closed you are likely not getting enough air to mix with the fuel.

Is that a manual choke or electric? If it's electric can you tell if there is power connected to it? If it IS electric and you have no power it may not be working. Mine is usually wide open and as the motor warms it closes gradually, reducing the amount of air pulled in.

Of course, other much wiser FTE'ers should chime in here as well. <o></o><o></o>

 

That looks like a fast idle solenoid.

 

Fish,
a flooded engine can take a while, maybe 15 minutes. You can use a little starting fluid down the carb to help out if you're impatient.

I don't know if a coil can be giving a weak spark; As far as I know they either work or don't work. I think it's safe to say if you're having problems and it's old, replace it with a new one that you know is giving you full voltage. Aftermarket ones can offer tons of voltage(which I think is overkill) over the stock. And while you're at it replace the plugs and wires too. That way you've eliminated spark as any source of trouble.

Your choke is the large "flapper" in the center of your carburetor. In the pic it's fully closed. It should be held shut by choke coil when the engine is cold and then open gradually as the engine warms up. The choke coil is the horizontal cylindrical assembly hanging off the passenger side of the carb. Your pic shows a wire attached so you have an electric choke coil. (check this for 12V) The choke or "flapper" should be vertical or wide open when the engine is at temperature.

The two circled objects are the "idle stop solenoid" and the other is the wire that's supposed to be attached. The solenoid had a pigtail wire hanging from it that fixes into the square hole right in the middle of your circle. It would have had the mating clip to your power wire which now hangs useless. The solenoid was a way of holding the throttle in the "off" position and can be adjusted to control curb idle speed. I eliminated mine and just reverted to the manual stop already on the carb.

Good basic info here on carbs; save and print the images when you need them....
| Repair Guides | Carbureted Fuel System | Carburetor | AutoZone.com

Idle stop solenoid from NAPA ($25)...notice the pigtail and clip

 

It's an idle stop solenoid, not a fast idle solenoid. A separate linkage mechanism controls fast idle on the other side of the carburetor.

To the other questions:

1. You should be able to clear a flooded engine by cranking the engine with the pedal to the floor within 30 seconds. Give the starter a break every 5 seconds or so. If that doesn't work, you'll have to walk away from it for a while. You can remove the plugs and dry them out to help in extreme cases.

2. If the coil is working, then you've answered your own question. You should only replace something if it doesn't work. If you're worried about it being old, you can test the winding resistance with a multimeter; that's about the best you can do.

3. When the truck is cooled off (as in sitting overnight), pull off the air cleaner lid, press the throttle, and you should see the choke snap shut. It's already closed in your picture, so it's not sticking open.

Also, great info from yankeerebel; I only have one correction - the stock electric choke connector isn't 12 volts; it's a three-phase AC signal. If you use a run-of-the-mill multimeter to look at it, it will "see" 7 or 8 volts DC (but that's not what it really is). You typically only see 12 volts DC for aftermarket carburetors.

 

Hey Fish,
now that I look at it closer, the wire you have circled IS the pigtail and clip from the Idle Stop Solenoid. It looks like someone pulled the black rubber boot off the back of the solenoid, broke the connected wire and left it lying on the intake. Just pick that wire up, I think it's just lying there. Then look for the male connector hanging from the wire harness nearby.

You may be able to re-solder it to the exposed end of the solenoid and slip the boot back on. The two prongs sticking out of the blue clip are what press into that square hole on the solenoid mounting base just under the white part of the solenoid. That holds the wire and connectors off the intake and away from heat.

 

Yes, that would have been ME that broke the dang thing. I was trying to figure out what it was last night when pop! it broke off. The pigtail was connected to the idle stop solenoid as of yesterday evening at about 5:30, but at 5:35 when I was trying to figure out what it was and what it plugged into, I broke it off then left it on the intake manifold. (I don't drive Patience right now, so no worries about losing it on the road.) Since I've had the vehicle (about a month), the female end had never been plugged into anything.

Patience got started no problem this morning. Her block heater had been plugged in over night (probably overkill), but this morning before I came into work, I started her up with no problems. Stepped on the gas once (to open the choke?) then turned the key with the gas pedal all the way on the floor. A few seconds later, she roared to life.

Regarding the ignition coil, I was under the assumption (wrongly, apparently) that old = weak spark. I guess this is not the case.

Honestly, I'm still unsure of what the proper starting procedures are for a carbureted vehicle. For those us (i.e., ME) who are new to carbed vehicles, is there a "standard" procedure for when the engine is cold? When the air temp is cold?

Thanks -

Fish

 

You should only be pumping the carb (throttle, gas pedal) a coooouple times on only really pretty cold days. And don't hold the pedal down to start, certainly not to the floor, if you're flooding, this is exactly why.

In my opinion, just turn the key like any other vehicle, if it doesn't start within a few seconds of cranking, touch on the gas (but don't hold it til it starts, that will flood), if the gas touch doesn't work, stop cranking, wait a second, and try again, maybe pump it once before turning the key, if that doesn't work, then maaaybe hold the pedal down while cranking.

If you get that far though, in above freezing temps, then you have some tuning to do. A well broken in engine like yours, should just be key and go.

AleX

 

The chokes on these vehicles aren't that complicated, neither is starting them, provided everything is working properly.

1. When the engine is cold, get in the truck and press the gas pedal to the floor ONE time. This does two things. First, if your choke is properly adjusted, it will slam the choke plate all the way closed. Second it will actuate the accelerator pump and squirt gas down the carb into the intake.

2. Turn the key to the start position. This provides 12v to the starter solenoid coil which energizes an electromagnet which closes the solenoid contacts which then provides 12v to the starter. As the starter starts to spin the gears extend, mesh with the flywheel and begin to rotate the engine. As the engine begins to rotate, this creates a vacuum which will draw air (and the fuel that you just dumped) through the intake into the cylinders. This vacuum will also open the choke plate ever so slightly. The air in the intake is replaced by air that is flowing into the carb which, again if the choke is adjusted properly will be quite a bit richer than normal operation for the sake of cold starting. Somewhere along the way the intake valve on the cylinder will close, the piston will start to come up, and NEAR top dead center your points will open up, allowing the coil to discharge across the spark plug. If everything is working properly it goes BOOM which slams the cylinder down to the bottom much faster than the starter and hopefully 90 degrees of crankshaft rotation later the process repeats and the engine then runs under it's own power.

It really is that simple. The key is that everything has to be adjusted properly. You have to have your choke set and working properly. Somebody mentioned it backwards, so just to clarify, when the engine is COLD the choke will be CLOSED, thus covering up the intake to the carb, effectively making the mixture richer. As the engine heats up the choke should slowly open up until it is completely vertical. Choke on your truck is very likely an electrically assisted hot air choke which will require both systems to be hooked up and working properly to ensure proper operation. For what it's worth, having the choke CLOSE is the "dumb" portion of the operation. If the electrical and hot air connections are completely missing the choke will still close if properly adjusted. The problem is that it will never pull off causing you to get about 7-8 MPG because you'll be running very rich all the time.

If it is REALLY cold you might need to pump the gas pedal 2 or 3 times when you first get in the vehicle. A safe bet, however, is to just do it once. I have found ever since I got my choke adjusted that this is all I need all the way down to 30 degrees so far. The more you pump the pedal, the more likely you are to flood it. Try just once and give it a shot, you'll be surprised how well it can work!

Honestly I would suggest that you go by your local parts store, buy a can of carb cleaner dip, a carb rebuild kit, and a new fuel filter. Take the carb off, disassemble it, and clean it completely. Put it all back together following the rebuild kit's instructions for your engine size (you never know what previous owners might have done) and then make sure your choke and idle speed is set properly according to FMC400's instructions.

While you're at it, buy new plugs (I like NGK), wires, cap, rotor, and points if it is old enough to use points. Set your dwell and base timing, then re-adjust your idle speed if necessary. If your coil is particularly ugly, do as others have suggested and check the resistance and make sure it is correct, take it off and clean it up and paint it if you wish, you'd be surprised how good you can make one look!

You may have to buy a few tools, one of which would be a timing light, but when it's all said and done you can get out for under $200 and assuming your engine is mechanically sound, it should start and run like a whole new truck!

You don't HAVE to do all of this stuff, but you'll learn a lot, and you'll be giving it a pretty thorough tune up at the same time. I drove my truck this morning and it was around 30 degrees. It started just as fast as any fuel injected vehicle I have and ran great, and that's just a dang good feeling.

 

...I was close.

 

Thanks for the tips on starting. That's great information!

Well, I'm in luck on one aspect. The PO gave me a carb rebuild kit for the 2150 that's on the engine. But, it still makes me nervous to pull apart a piece of equipment that is completely foreign to me. I guess the benefit to rebuilding a carb would be that after the rebuild, it would no longer be foreign. The exploded view on the instruction sheet looks incredibly daunting. Unfortunately, the rebuild kit instructions do not have adjustment specs for a 390. Does this mean that either a) I have identified my carb incorrectly or b) there are multiple rebuild kits for the same carb? The kit I have is a NAPA 2-5840. How much time should I budget for rebuilding the carb? Soak overnight in carb cleaner then 4 hours? 6? 8 hours?

I like your idea of a full tune up. A timing light would indeed be a purchase I'll need to make.

Oh, and it's been really cold here recently. Last week, highs were in the negative values F. Thankfully, temperatures are creeping back up to normal - 20s and 30s.

Thanks for your advice -

Fish

 

Well for what it's worth, the carb was foreign to me too before I took it apart. The instructions aren't all that great but really if you're mechanically inclined at all it shouldn't be that bad.

I didn't soak mine overnight, but it wasn't THAT dirty to start with either. I did the whole project start to finish in about 2-3 hours and did so sitting on my front porch. If you have a nice well lit work area and can keep little parts separated I imagine you could do it even faster.

It was a pretty hot day so I remember I pulled my truck up under my big maple tree and ripped the carb off. I took it all apart and then had the joy of trying to race the weather putting it back together. It started to blow up a nasty storm and I needed to get the carb back on the truck so I could move it. I just KNEW that if I didn't move it the storm would knock a big limb out of the tree and bye-bye truck. It was raining when I got it to move, but I didn't get TOO wet.

As far as the adjustments, they may have just not included them with the kit. If I remember correctly it tells things like choke pull off opening, accelerator pump settings, etc. I think some dip had set the accelerator pump on mine up for a 390. In any case I do believe I still have the package and the instructions that came with my kit. I'll look in the morning and see if it has the settings for a 390 and get them to you if it does.

Oh, if you don't already have one you may wanna get a vacuum gauge too. It's about the best way to dial in the idle mixture.

 

Fish, this was my first carb I ever rebuilt, save little 2 strokers.

If you've ever built a model car before, you can rebuild a carburetor. Take your time, and take pictures. Here's a good step by step on how to rebuild it.
http://www.therangerstation.com/tech..._2150_carb.pdf

Budget how much time you want, but the longer you soak the carb the better. I soaked mine for 4 days. That's a little excessive, but it ran great. After that, it took about 3 hours putting it together and setting up all the choke adjustments.

And the carb kit you have can be used for the 2100 AND 2150 with multiple engines.

 

So I'm going to pull the carb off today (before the SEC Championship game - WAR DAMN EAGLE!) and let it soak overnight to rebuild tomorrow. Is there anything I need to put into hole left in the intake manifold to keep crap from getting in there? Is it okay if I just stuff a rag in there or something?

Also, I'm assuming that all vacuum lines/throttle linkages are easily disconnected from the carb? In other words, removing the carb is as simple as removing all of the connections then unscrewing the carb from the engine, right?

Thanks -

Fish "with a healthy dose of trepidation" Scientist

 

Throttle linkage simply unsnaps from the side of the carb. If your carb still has the hot air choke you will need to disconnect that carefully and unplug the electrical part of the choke. Otherwise there are about 4 bolts and a number of vacuum lines and it'll come right off.

A rag will do just fine for blocking the holes in the intake.

Personally I would suggest disassembling the carb as much as possible and letting the individual components and such soak. Soaking the whole thing as a whole might not do all that much good. This may be what you intended but just figured I'd say it anyway.