1985 F-250 6-cylinder, stick
Carburetor: Motorcraft E5TE BA

An unregistered old truck that I now just use for plowing my drive. Runs fine in the summer, once it starts (I seldom use it), but as soon as it gets cold, it is a real problem to start it. Turns over for a while before it finally fires up. Will run for a time, but if I put it in gear and try to move it, it stalls. I took the carb off last fall and cleaned and rebuilt it, but it only helped marginally. Preheating the engine seems to help some, but ....

First day of temps in the teens last night. Started hard this morning, and ran for a while, until I put it in gear and tried to move it.

Once it stalls, it is a bitch to start again. If I take the air cleaner off, a light bit of smoke comes drifting out of the top of the carb. If I put a few drops of gas in the carb, it fires up and runs well for a few seconds, then nearly stalls, then runs well again, then nearly stalls, repeating this cycle for about 8 times before it stalls completely (my guess is that the few drops of fuel are finished). Doesn't matter whether I hold the gas pedal down or don't touch it. Fuel pump works fine, and it has a new fuel filter. (No apparent frost on the carb as when it ices up, which it has been known to do often after driving for five miles on a 0° day, or five minutes of plowing in a storm.)

Obviously something is not right in the carb, but I followed the directions EXACTLY. Unfortunately, the truck is not register for road use and the nearest Ford mechanic is half an hour away. (They like GM products around here.) So, any help from you experts would be appreciated. Thank you.

 

Sounds like the choke is not working right. The choke is the large door on top of the carb.

On a cold morning if you take the aircleaner off, you should be able to push the gas pedal to the floor once, and the choke door should shut. As soon as the truck starts, the choke door should crack open just a fraction of a inch. This is the choke "qualifier" or "choke pull-off". This is usually operated by a vacuum diaphragm somewhere on the carb, and keeps the engine from stalling by having too much choke. In your rebuild instructions, there should have been a spec for this. If it cracks open too far, the engine will stall. If it doesn't open enough, the engine will run rich and stall.

After the choke door cracks open(and the engine shoudl be idling fast) it will sit there, and depending on how cold it is, the choke door will slowly start opening up. If you kick the throttle, it may open more. The rate that choke opens is determined by the choke adjustment by turning the large round black piece. If it opens too fast, it will stall and be hard to start. If it doesn't open fast enough, the engine will run rich and use a lot of fuel.

 

also make sure the accelerator pump works, with no choke you should be able to pump the gas enough to get it/keep it running

 

yup thats what i do on my 85. pump twice, crank while pumping. she will fire up but you got to keep pumping for a few seconds before it will hold 1500 rpm with trottle. basicly making a rich mix by nearly flooding it. my choke will do nothing untill it is under 20`F then it only engages 1/2 way

 

Thanks for all three of your replies. It turns out that the clip that holds the accelerator cable onto the ball of the carb was not tight enough to keep it on, but from the position I could see it, it looked fine. Of course, being in the cab meant that I couldn't see the cable move when I push on the pedal. Once I squeeze the clip, it stays on fine and the engine fired up nicely, and I was able to keep it running.

But getting out of the cab, the engine started to race then slow down, over and over again, while the auto choke lever, going to the diaphragm, went in and out. I adjusted the choke idle screw until it ran smoothly, but then when the choke opened fully, the engine started to fade again. I tried to adjust the other idle screw, but it was already compressing the spring completely. Seeing that the two idle screws were different lengths, I swapped them and was then able to adjust the idle properly. Then when the engine heated up, the idle was way too high. By then the engine was hot and I had to go. It will be about 15° tonight, so I will see what happens tomorrow, but obviously, I still don't have something right.