Cbystrack

i have an in tank walbro 255 pump to my holley blue 3 port return style regulator..... if i hook it up the way you think i can only adjust from 3ish to 6...... i need nine +psi...... its a brand new regulator... any input from everyone. did i hook it up wrong??? center port says in.. so i put fuel feed in, then there is two outs... i followed the arrows one for fuel to the carb, and one for my return??? please correct me if im doing something wrong. thanks



1987 camaro iroc-z

ws6transam

You need nine PSI for a carbuerator? I always figured that 6 PSI was sufficient for a carb application, since all the fuel pressure is needed to do is simply pour fuel into a float bowl and keep the fuel from flashing to vapor within the fuel line. Most carbuerator manufacturers recommend no more than 8 PSI of pressure. Remember that when using a carbuerator, the fuel is atomized via a venturi, which passes a fast-moving column of air over a pilot hole. The fast moving column of air within the center of the venturi is a low-pressure region, and when the fuel gets slurped up the pilot hole and hits this high velocity air column, it is torn into atomized vapor and mixed with the air column. You don't need any fuel pressure to atomize fuel, like you would with an injector. The fuel pressure need only be sufficient to keep the float bowl topped off with fuel. Extra pressure can actually overpower the float, needle & seat if it's at all imperfect, and over-fill the bowl. I'd give the 6 PSI a try. You could always try swapping the return ports to see if that makes any difference. Also, I am wondering if perhaps your Holley regulator is designed to be a returnless, and that second port isn't a bypass port, but an outlet for a second carbuerator?

Cbystrack

it could very well be as you say for a second carb.... BUT. when i block the return off and plug the second port on the regulator its getting 46psi as if it werent even hooked up.......

I just saw at a car show someone had the same regulator i have and they used the second port for a pressure gauge... im assuming there running an out of tank pump as they were not useing a return line....

As i said i am new the useing/tuning a carb and im getting better just dont understand why it runs so much better with 9psi aposed to 5-6psi.... now mind you its a built 355.....they guys i know say there sure its anywhere from 8-9psi with what im looking for but the forum is here for questions and thats what im doing haha.

when i run the 6psi its not responsive really at all.....now when i got the 9psi on it she is as good as fuel injection.... im lost i know any ideas???

ws6transam

If, at 6PSI, the engine starts stumbling, then perhaps you are indeed running the float bowl dry. It's not fuel pressure that would necessarily be the problem but fuel volume. Boosting pressure will get more fuel-per-second into the bowl, but so would having a larger feed line or a less restrictive fuel filter. You could also try raising the float height in the bowl a few millimeters. Also, if I'm right, you are probably experiencing power loss a couple seconds into the run, not straight out of the hole. If all else fails, try a different brand of fuel pressure regulator and set it to 9 PSI.

Z28SORR

Pumps that are designed for carberation usually have an internal bypass and are set for lower "carb" pressures.
What is the size line that you have from the tank? You should have a minimum of a -8 line from the tank to the regulator, and a -6 line to the carb.
If you get pressure at the carb. which is to high it can cause the inlet seat (float valve), to open and over fill the float bowl/s. This can cause anything from a rich mixture to fuel spraying out the float vents and FIRE.

Cbystrack

well i am useing a walbro 255 in tank pump and i figured that would have suffecent volume to the regulator...it may be a matter of my TV cable out of adjustment a bit which i plan on messing with a bit to see if it clears things up... its only when the tq converter locks up... its fine on the throtle but when i let it go to coast and get back on it she stumbles until it kicks back down.... it has power....def has power its pretty responsive. i am running a stock fuel injection fuel filter under the car and an inline fram see through fuel filter before the carb... maybe i should bypass the stock fuel injection filter??? As far as fuel lines there stock for fuel injection and dont plan on upgradeing until winter as there 3/8's feed and 5/16's return if im not mistaken.......thanks everyone for all the help so far. this forum is a huge help

AutoRoc

I ran a 255l walbro 340m in tank pump with stock fuel lines and it fed my 600hp carb sbc just fine. I even had an oem style inline fuel filter in there still. I have used a mallory return style regulator and also an aeromotive brand return style regulator. The bottom ports were always the return ports.

You do NOT need 1/2" fuel lines... hahaha

You sure its a return style?

5-6 psi usually works best . 9 psi always made the carb overflow.

Cbystrack

prob solved... i have the low pressure regulator and its good for 1-7psi and have the high pressed regulator on order and should be here by tuesday 4 1/2psi-9psi should fix my issue! thanks for the help everyone once again!