Hello, my name is Mike and I just joined the forum today. I'm located in Richmond,Va and grew up driving my dad's '71 Sport Custom. Loved every teenage moment I had in that truck and recently purchased a couple for myself.

Read the last guys' post about his 351 having problems starting up and running in cold weather. Mine has the same problem, only I,ve got a 1978 f-150 Custom with a 300, straight six, 3\-on-the-tree. It came with a Carter YFA carb, model 7174S and I cannot for the life of me figure out why it does not run in the cold. Here's the main issue. There is a wire coming off the back of the electric assist on the automatic choke. In some trucks I have seen in the junkyard, this wire connects to the back of the center post on the alternator. However, on my truck, there are already wires connected to that post, so I have no where to hook up the electric assist wire. In warm weather, the truck runs like a champ. The truck floods gas in the cold as the choke plate does not close fully. Now I am an idiot when it comes to automotive technology and terminology, so I will really need some help here.

Last year, I got a remanufactured carb from the junkyard, Carter YFA, Model 7460S and put it on the truck. This carb had a few extra things on it, like fuel bowl vent rod, throttle lever/actuating lever on the front, dashpot on the back, etc. i take this was an upgrade for other items on later model trucks, yet still fit onto the Carter YFA carbs. Hooked up the newer carb and the truck once again ran fine. Adjusted the curb and fast idles and couldn't have been more happy. Cold weather is here and it doesn't do squat. I had my father-in-law help me out with it and ended-up with with a big pile of nothing. Put the old carb back on, it idled like a champ, and then he messed around with the idle adjustments and mixture limiters and it barely starts up. I'm pissed to say the least and I need some answers.

Lastly, we took out the newer plugs I had installed with the Belco wires and there was a pile of oil and crud around the electrodes. I'm sure there might be gas entered into the oil or worn valve guides or piston rings. In the warmer months, however, it couldn't run any finer.

I only know the terminology I am using because I purchased the truck shop manuals for my truck off of eBay and have been trying to teach myself about this truck. I also have another 1978, but it's an XLT Lariat that is immacculate with only 86,000 miles on it. It stays parked in the garage for the most part and has a 302 with an automatic. I LOVE driving my beater with the 3-on-the -tree and could really use some expert advice. Thanks for anyone's help and keep on truckin'

 

If the mixture screw is out of adjustment, just screw it all the way back in (finger tight only no more, clockwise) then back it out about 1 1/2 turns. This should get you in the ballpark enough to allow it to start. After the engine has warmed up, get a vacuum gauge from your local parts store and hook it up to a vacuum port on the intake, or the lowest one on the carb. Once you get it running, turn the mixture screw about an 1/4 turn at a time in either direction that shows in increase in vacuum on the gauge. Continue to turn the screw in the same direction (a bit at a time) until the on the gauge starts to fall back, then turn the screw in the opposite direction about 1/4 turn.
You may have to adjust the idle speed screw after doing this as well to get a decent idle speed of around 800 rpm. Turning the screw clockwise increases the speed and counterclockwise reduces the idle speed.
To get the choke setup correctly, you almost need the directions from a carb rebuild kit as it lists the proper gap that needs to be between the choke blade and airhorn (when closed) to operate properly. A fraction of an inch either way makes a big difference in how well the choke operates.
I'm not familiar with what type of choke coil the YF carb has but there's usually a round plastic housing on the side marked lean and rich. Loosening the screws that hold the cap on and turning it, determines how long the choke stays on. Leaner will make the choke open sooner and rich will keep it on longer.
It's kinda hard to describe stuff like this over the internet, but hope this helps.

 

Jade, thanks for the info. A Quick update. I went to the junkyard on Sat. and found the wire I was looking for that goes to the electric assist for the choke. It hooks up to a connector located on the cowl and then runs over to the solenoid. I will post some pictures tomorrow when I try hooking it up. Also, found a manual choke cable from a '69 Ford and I am hoping that I can use that as a backup if the automatic choke doesn't work.

Anybody know how to mount the manual choke cable to a Carter YFA carb after taking the automatic choke off of it?

 

They do sell a kit for this and I wanna say the holley one will fit as well.

 

The electric choke gets it input voltage from the alternator stator output. With the engine at idle; check for about 6-7 volt dc at the choke electrical connection. The voltage input to the choke is really a pulsating half wave DC wave form, thus the lower voltage and your meter reading might vary due to the half wave signal. If the voltage is present, you need a new electric choke coil. That is the black cap on the back side of the carb attached with 3 screws.

Also you might have a hot air source from the exhaust manifold that will cause the choke to open, it just takes longer. Look for a pipe going into the carb from the exhaust manifold.

Jim

 

More choke info: https://www.ford-trucks.com/forums/8...ml#post6939116

 

Well, I will tell you what. Never have agreed with an automatic choke. I don't like them when they don't work, and because I don't know what that choke is doing under the hood. I owned a 1984 f150 with the 300 inline. Some one put a manual choke on there and even though the engine was quite misstreated and wore out, it will fire up no matter how cold and all. All I had to do was pull that choke closed and hit the key till she fired right up. Enjoyed the function of a manual choke on my trucks sooo much that I miss it really. One of these days I will have another carbed truck. But, it shouldn't be hard to put one on. Just make sure it is adjusted right. I'd say to just go with a manual choke if that is part of the problem. Just make sure your girl friend/ wife doesn't pull it out to use it as a purse holder, joking, joking. But, really I've never had a manual choke let me down. Worked exelent for me no matter how cold.