Holley acc pump issue.

been helping a friend get his 70 AAR cuda running better, 6 pak is long gone and has been running a single 4 on it, he had a Edelbrock carb on it for a while, ran good but was a real bear to start after running it for a while, so switched to a Holley 650 dp he got from a friend, car ran, idled, and started much better after the swap but had a noticable stumble when you took off from a stoplight or anything, so we did the normal squirter swap,,nothing, changed the pump diaphragm,, nothing, even pulled it apart and checked the gasket and cleaned the circuit,,nothing what I did notice was when you give it a little throttle no gas came from the squirter untill you gave it more throttle so i took the squirter out and moved the throttle just a little and gas would come up in the main body but as soon as you released the throttle the level would drop as if it is draining back leaving a air gap between the main body and the squirter, so I put in a new check needle below the squirter and nothing,,all that I can think of is the check needle seat is mis machined or damaged(how I don't know) in the main body, can this be fixed or is it time for a new body? other than that the carb works excellent.

Sounds more like the lever arm that engages the squirter is not adjusted correctly. Set the squirter arm to the adjustable bolt so that it barely touches or has a .004" gap, no more. Its the bolt that has a spring on it, and uses a 3/8" open end on both ends of it to adjust. Do the back one as well.

adjuster arm has been set and re set two different ways with the arm just barely touching and approx .015 clearance (additional travel) before bottoming out at full throttle, niether way had any effect, just don't understand why it bleed's back.

Did you check the inlet check valve ? It is usually the flat red rubber type in the bottom of the carb under the pump. I only ask because to me when you have the pump discharge ball or weight in the circuit it will drop as soon as the pump stops to keep fuel right there and then the inlet check valve should open and let fuel in the circuit to keep a full and ready pump shot. Then of course the invlet valve should seat and seal so it has a full shot of fuel in the pump circuit. Ron
.

Quote:

---

Did you check the inlet check valve ? It is usually the flat red rubber type in the bottom of the carb under the pump. I only ask because to me when you have the pump discharge ball or weight in the circuit it will drop as soon as the pump stops to keep fuel right there and then the inlet check valve should open and let fuel in the circuit to keep a full and ready pump shot. Then of course the invlet valve should seat and seal so it has a full shot of fuel in the pump circuit. Ron
.

---

Make sure the rubber is laying flat and not dried/wrinkled up some. Also, the squirter check seat can be possibly straightened up with a small pin punch, set on top of the check needle, and then tapped with a hammer.