ok i have done a very intense cleaning and rebuild of my carb. 250 inline single barrel. truck still will not run without the choke on, even with it on cant pull a hill or get above about 45 mph. i checked vacuum in the intake and its right on 20, that is with the choke on because thats the only way it will run. if you turn choke off you can hear a sucking sound from carb and engine dies. i have checked all possible vacuum leaks found none. could this possibly be in the ignition timing??
It sounds more like it's starving for fuel more than anything. Have you checked your float level or fuel pump (volume pressure test) or your fuel line to see if it is plugged? Or maybe even the fuel filter is plugged. It doesn't sound like a timing problem.
tim i agree thats what it sounds like to me or maybe vacuuml but i have started the truck sprayed carb cleaner all around base of carb, the intake everywhere no detection of a leak at all. it all started about 2 mo ago when i put in a new clutch and pressure plate. it ran fine till i put it on the ramps for two days put the clutch in and started it to back it off the ramps thats when the trouble showed up. just cant figure it. i would just put a new carb on to try that but the darn things are about $200 hate to spend that kind of money not knowing its the problem. new fuel pump, great fuel pressure, new clean lines etc. new filter.
while the engine is running try spraying some carb cleen in to the carb and see if it will run with the choke open. This will tell you if it's a lack of fuel problem. You said you rebuilt the carb, so I'm sure you checked the float level but did you run some tag wire through all the passages particularly the main jet passage? Some times you can cross 2 plug wires and crack the throttle a couple of times and it will cause the engine to backfire up through the carb and blow out what ever is plugging it up.
after much blood, sweat, and prayers found the problem. dont know what its called but there was a small brass plug not much bigger than a tylenol that plugs into the end of a tube on the bottom side of the air horn. it had come out, not sure what was supposed to hold it in, but wrapped it with teflon tape put it back in hole and fired right up running great far as i can tell. anyone know what that may have been. not in any of the diagrams i have.
