Results 1 to 3 of 3

Thread: Holley primary booster dripping at idle.

  1. #1

    Default Holley primary booster dripping at idle.

    New rebuild, now booster drips at idle. I've tried a very low float level, no luck. Air bleed is clear.

  2. #2


    Very weird. Only way for fuel to drip out the booster is if there is a "siphon" effect going on or pressure issue. Pressure issue would be caused by the needle & seat not properly shutting off incoming fuel. I know you say you have tried different float level, but are you 100% sure the incoming fuel is being "SHUT OFF" at float level. Do you have a site glass on your fuel bowls? What's your fuel pressure at? Possible you over pressuring the carb?

    Do you have an electric fuel pump? If so, turn the pump (don't start the engine) on and watch the booster. Is it still dripping? If so you are either over pressurizing the needle & seat or the the needle & seat is not properly closing. If you have a mechanical fuel pump, unplug power to the distributor, have someone try to start the car for 7-10 secs. While turning over is the booster dripping? If so, same thing as above. Either needle & seat not seating properly or your over pressurizing the needle & seat.

    If the carb does not drip from booster during any of the above scenario, then you your IDLE air bleeds/passage may be blocked, allowing a siphon affect to happen with a very low negative pressure. Main boosters normally will not start flowing fuel until the engine starts to turn 2000 RPM or so. There has to be enough air flowing through the booster to create a SIPHON (negative pressure) affect. Plenty of you tube video showing this. Hope this helps you find your problem

  3. #3


    Take it apart, and clean it again. One of the orifices is plugged that's supposed to "let" in air. Example: Take a straw and poke a hole in it. Try sucking a liquid with the straw, and the hole (above the liquid) not covered. It will be "hard" to suck the liquid. Now "plug" the hole and try sucking the liquid through the straw again. It will be very "easy".

    And make 100% sure the float levels are right. There are some passageways in Holleys that have to be covered with fuel, or they start acting "funny".

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us