I am helping a friend troubleshoot his Holley 850 double pumper. When the engine is off the throttle returns as it should. When the engine is running the throttle does not return to idle. Any thoughts? Thanks for any help you can give me.
Jeff

 

is there any interference between the throttle blades and the intake manifold or intake manifold carburetor gasket?
Do you have a double return spring?
The choke is fully open?
Have you tried disconnecting the throttle cable and manually opening the throttle to see if it still sticks?

 

How is the electric choke set up?

On mine(holly double pumper, not sure if it's the same one or not) there's the elec choke spring adjuster which gets more tension when turned counter clockwise, and a few linkages with a red plastic piece which pops into place when the choke spring is cold... It holds the choke idle screw in a partial throttle position... Then later when the choke spring coil is warmed up, tapping the throttle allows this red plastic piece to drop, therefore not allowing the throttle to be in the open position...

There's a little screw with spring on the right side of the carb, that will come in contact with the red piece, which will set your choke idle position... Turning in adds more choke Rpms, turning out will be less...

Currently, mine is set to keep the motor running when dead cold, blip the throttle once before start, it sets the red piece and engages choke idle speed, then I fire up the car, and it will idle at roughly 800rpms for 30 secs or so til it starts to get warm and then smooths out and climbs Rpms... It will go up almost to 2500 Rpms before I hop back in and blip the throttle again... Then going back down to ~600 Rpms when warm...

If you are trying to start the car after the key has been off for a little while, the choke coil spring will always cool down this engaging the choke again... Is this the symptom you're describing? The other way to eliminate this is just leave the key in the on position, wait until you see the little red slider go down and the butterfly stay full open..

 

Thanks for your comments. We completely removed the electric choke to test that and it had no effect. The problem is that the throttle only sticks when the engine is running. With the engine off it never does. My feeling is that the bushings on the shaft are worn and the vacuum of the running engine slightly pulls the throttle plates off center and causes them to bind. Does this make sense to anyone?
Jeff