My Holley carburetor-equipped vehicle has a stumble from a dead stop. What can I do to fix this?
The most common cause of a stumble is not having an adequate accelerator pump shot. The first thing to do is to look at the discharge nozzle and make sure you are getting enough fuel. If not, then you need to inspect the pump diaphragm for a hole or tear. You should also make sure that the pump passage is clear of trash or debris. Next, check the adjustment on the pump. To do this, open the throttle all the way. Push the pump arm lever down and adjust the pump override spring to obtain .015" clearance between the pump arm and lever. If you have a stumble and no black smoke out of the tailpipe, then you will need to increase the shooter size. If it stumbles and you are getting black smoke from the tailpipe, then it will be necessary to decrease the shooter size.