I installed a used (less than 5000 miles) Holley 4 barrel that floods after the engine is shut off. Carb has been rebuilt to try to solve this problem but that didn't help. I installed a Holley regulator which also didn't help. I've posted a video to show what its doing http://youtu.be/4WWd0tBD2F4 (forgive the out of focus in the first half). The fuel pressure runs around 2.5 - 3 psi when running which is fine, but after the engine shuts down, the pressure climbs until it overcomes the needle and seat valve and dumps fuel into the intake. I can squeeze the line from the carb to the regulator and cause the pressure to pulse. Squeezing the line from the pump to the regulator has no change so I think the regulator is working fine. I should add that the issue happens when hot or cold. Any Ideas?
We put new needle and seats in. Checked float levels. This carb has non adjustable floats. They have to be set dry with the bowls off.
I'm assuming that when you say it's flooding it's pushing fuel out of the bowl vents on the top of the carb. First, a holley needle & seat should hold well past 4 psi, so I'm guessing there's dirt on the seat or its defective. Second, have you opened the sight holes on the sides of the bowls to verify float level is set correctly? Third, I've never seen a Holley that you couldn't adjust the floats with the fuel pump running. That's how you are supposed to do it. It's accomplished using the float adjusters on the top of the bowls.
If the float assist spring is in place, I'm not sure that's a carb problem... Fuel pressure will rise at shutdown due to heat soak, I always assumed it was the fuel pump's job to bypass the excess pressure back to pump inlet and tank... BTW does the carb have any sign of corrosion inside??? I had one the plating inside was flaking off and was covered by replacement policy Holly has in place(just earlier this year)... Has to be mfg'd in late '05 to mid '06 to be covered... They made 'em(dunno if they still do), the one I mentioned above had non adj floats, can't remember if it had sight plugs or not... When I sent it back I asked if it was possible to pay difference for a model with adj floats... Never heard anything but when replacement came it has adj floats...
This particular model Holley has no external float adjustments or a sight plug. It's a lower end version of the 4160 I believe. I swapped the fuel bowls with an adjustable bowl just to test and the same thing occurred. So as of now it's had 3 sets of needle and seats. The original, the new from the kit, and the ones from the adjustable bowls (which work on the other carb)
It could just be fuel boiling or expanding after you shut down a hot engine. You may need a plastic or phenolic carb spacer to isolate the carb from engine heat. It's coming out the vent tubes?
what does the fuel pressure rise to when the motor is turned off? at what pressure does it start coming out of the carb?
What fuel pump is feeding it and where and what type of fuel line is used between the pump and carb ?
I don't have access to the donor carb at this time. It belongs to a friend. Here's some pics of the one I'm working on. I've come to the conclusion that the main body has a hairline crack. When I look into the secondaries after the engine shuts off, I can see the throttle plates become wet and a horizontal line of fuel that starts about halfway up. Looks like its time for shop for another carb.
no.. its seeping into the secondary throat through the wall between the secondaries and the float bowl, about halfway up. I have a call into Holley... their headquarters is only 20 minutes away. They're supposed to call me back next week. Hopefully they'll take a look at it.
