Help! My truck starts, then dies

[pjmoreland]

I'm struggling with a problem with my truck. When the engine is cold and I start it, it starts right up, but then after about 5 seconds, the engine stumbles and dies. If I time it just right, I can keep it from dying if I pump the gas pedal lightly and quickly. But then about every 5 seconds or so, the engine starts to die again. I have to repeat the pedal pumping about 10 times. Then finally after about two minutes the engine will idle consistently. It usually ends up dying when I shift it into gear. It's quite an ordeal to get the truck going in the morning.

The carburetor is a Quadrajet with a heat-activated coil choke. The choke closes completely when the engine is cold and the gas pedal is tapped. Once the engine starts, the vacuum diaphragm pulls the choke open and the engine runs at around 1300 RPM before it dies. I have the idle mixture screws adjusted to give the highest RPM. They are screwed out about 1/2 turn.

My timing is adjusted at 10 degrees. I'm at high altitude, and I've been told that the extra 2 degrees help with the thin air. All spark plugs are firing consistently.

Once the engine is warm, it runs great. Any ideas? Thanks for the help.

[ZOOMY]

Your choke pull-off diaphram is pulling the choke open too far, allowing the mixture to lean out enough for the engine to die. Cold engines need a rich mixture for awhile too keep running. You'll have to adjust (bend) the rod to the pull-off so that it opens the choke a little less. It's a trial & error thing. If you don't go far enough, the engine will keep dieing. If you go too far, the engine will load up with excess gas and run real rough and might even die from too much gas. When you get it right, it'll stay running even when you put it in gear. All of this trial & error has to be done with the engine cold.

[pjmoreland]

Thank you for the advice. That makes sense. I'll give that a try. I did notice that the choke does open just about all the way once the engine has started.