Posted by gmharris [71.105.36.203] on Sunday, February 02, 2014 at 21:30:41 :
In Reply to: Duh! posted by Sherman in Idaho [72.47.153.112] on Sunday, February 02, 2014 at 19:05:24 :
Hmmm, that could be a clue. You should be able to kill the engine either way (full rich or lean) at idle or at least make major changes in the way it idles. However, having the choke pulled out may be overriding the idle circuit, if that's when you're adjusting it. Also, make sure you aren't idling so fast or have the throttle plate open so much that you are off the idle circuit.
What kind of idle vacuum are you pulling with and without the choke? Does it have 17 inches of vacuum when it dies? That could be a clue too.
Do you have vacuum wipers? Could be problem with a leak at the wiper motor end. I'd pinch of the wiper hose at the manifold to be sure.
I saw a thing on T.V. recently where the guy was checking for vacuum leaks with the torch (acetylene only) from his oxy acetylene outfit. Be careful you don't saturate the area to a point the atmosphere becomes explosive.
And it doesn't hurt when trouble shooting to make sure things like timing and dwell are good.
You have done a pressure and volume test at the carburetor, haven't you? Seems to me to be the most likely cause.
You say the truck won't run unless the choke is pulled out. Is this only at idle or at speed when you are driving it? If you are driving it, does the engine stall when you step down on the gas with and without choke?
Can you get it to run above a fast idle without the choke? If not, I would suspect the fuel supply or the needle valve is the problem.
An auxiliary gas tank with gravity flow should eliminate the fuel supply as a source of the problem. I have a small lawn mower tank that I put on the roof when I'm trying to eliminate fuel supply..
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