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wildb 03-30-2013 09:35 AM

holley street avenger problem
Hey all, new to the site. sorry if i'm posting wrong or wrong place, but i need help.
1987 chevy V10 4x4 350. originally tbi, just rebuilt engine, using orig. intank fuel pump, return style reg., upsized return line. new performer intake w/ street avenger 670. fuel press. @ 5psi.
fuel shooting out front vent tube.
cleaned bowl, needle & seat, adjusted float level-same problem
new needle & seat, new brass float, adjusted-same problem
cleaned all again, another new needle & seat, adjusted float up & down, dropped fuel press. to 3psi-same problem...
HELP--any ideas? :confused:

ssmonty 03-30-2013 11:53 AM

Are you adjusting the float so that fuel just barely gets to the bottom of the site plug opening(not dribbling out) while the engine is running on level ground?
Try removing the gas cap from the fuel tank. There could be pressure building up in the tank from too much fuel returning to the tank and foaming up. It could be that the regulator gets a reference from the return line. If the pressure on the return goes up(pressure in tank rising) then the regulated pressure might go up the same amount(still only 5psi above return)? Is the tank vent clear? Worth a try.
Do you have a "T" fitting just before the carb that you are using for the fuel gauge while its running? Have you tried another fuel gauge?

PatM 03-30-2013 12:35 PM

Sounds like too much fuel pressure. I'd be very suspicious of the regulator and gauge. What regulator do you have?

wildb 03-30-2013 12:51 PM

regulator is a holley 12-803bp, press. gauge before carb, + used a new vac/press gauge to check other gauge. same reading. return & vent lines clear.
possible problem with the bowl???

wildb 03-30-2013 12:55 PM

have pressure down to 3psi, float adjusted all the way down (limit of adjustment), fuel trickling out of site plug. cannot lower float any more. truck not running yet, been doing all this with switch for fuel pump.

PatM 03-30-2013 01:37 PM

Did this reg come with a low pressure spring? From what I could see, this is a 4.5 - 9.0 PSI unit. If it did not come with a low(er) pressure spring, I'd still be a bit worried about the gauge.

You might also want to test the sealing of the float valve. Since you're not running the engine, any leakage thru the valve, particularly if coupled with very slight leakage at the regulator, would cause this inability to fully shut down the flow. Have you tested the float valve with the bowl off the carb?


wildb 03-30-2013 01:51 PM

not sure about the spring, 2 different gauges tell me 3psi. tested bowl off of carb, ran 5psi air thru fuel inlet, pushed float up gently, needle shut off air flow as soon as it seated.
don't know what else to try. leaning towards flaw in bowl. going to try buddies carb, we'll see what happens. i will let you all know.

this site is great! been reading thru it for a long time, found lot's of help here.
you guys are what it's all about. awsome help. thanks much!

PatM 03-30-2013 03:16 PM


Sorry, I thought you had the 12-803b regulator. From what I see the 12-803bp is preset (hence the p?) at 7 PSI. Is it the adjustable regulator with the pressure simply pre-adjusted to 7 PSI? I'd have thought that any adjustment would've been locked out, but I'm not acquainted with this particular regulator.

With your finger lifting the float, clearly you could easily exert much more pressure on the valve's sealing surface than the float (on gasoline) would be able to exert. You might want to try an underwater bubble test looking for defects in the float bowl or very small leakage paths through the seated valve. Remember, with the engine running, a very small amount of leakage can be accomodated by the engine's demand for fuel. With the engine not running, any leakage will result in fuel slowly trickling out through an open sight glass.


wildb 03-30-2013 03:50 PM

just swapped out carb with working Edelbrock. double check fuel press with 3 different gauges. 3psi at reg exit. pinched by pass hose to see if working. press jumped to +10psi. unpinch press back to 3psi. hooked fuel line to 2nd carb., turned on pump, fuel coming out of vents.
i am working about to have a bald spot on my head from scratching it about this deal...

i thank you for all your input.
i am baffled at the moment....have a cold beer on me & thanks

wildb 03-30-2013 05:19 PM

( not sure if it would make a difference, but all testing & carb problems have been without the truck running. waiting to break in cam.)

wildb 03-31-2013 11:04 AM

Happy Easter All...

wildb 04-01-2013 06:54 AM

Ok,,,new update. Put the avenger back on, another new n & s. Installed mechanical fuel pump, hoping to suck through in tank pump. put gauge inline before carb. went to crank engine without electric pump running. gauge reading 3psi. fuel out vent tubes. ?????????? i'm lost now. 2 different carbs, 2 different pumps, floats, n & s's, adjustments. Any ideas???

PatM 04-01-2013 11:14 AM

Unless the engine is mounted upside-down, or your gauges measure bar instead of PSI, this is all I have left. . . . . "You might want to try an underwater bubble test looking for defects in the float bowl or very small leakage paths through the seated valve. Remember, with the engine running, a very small amount of leakage can be accomodated by the engine's demand for fuel. With the engine not running, any leakage will result in fuel slowly trickling out through an open sight glass." . . . .or the bowl vent.


Edit -- N and S is not registering.

ssmonty 04-01-2013 04:52 PM

I've got to say your not adjusting the float correctly. You said fuel was trickling out of the site plug.
You should be able to keep it from coming out the site hole unless you have too much pressure! Its not coming out the vent when you have the plug out right? If its coming out the hole, how do you know its not still rising after you put the plug back in? It could just keep rising to the vent if the seat isn't low enough to let the needle contact it when the float rises(of coarse). No need to put the plug back in until you get fuel to stop coming out the hole.
You are turning the large nut clockwise while holding the slotted screw stationary aren't you? At least I think thats the right direction. Its been awhile.
Sorry if I'm coming across with a little bit of a frustrating tone.

wildb 04-03-2013 03:32 PM

Sorry guys, been a little busy. New update...dropped tank, pulled intank pump, installed mech pump & bypassed regulator. Truck cranked on second spin, NO fuel out of carb vents, all adjustments now in spec's.

My take is the CONSTANT pressure from the intank pump is too much for the carb to handle, even with the regulator set @ 2.5 psi. Not quite sure how those guys who say that they use the intank pump & regulator are getting it to work. I tried everything.:confused:

truck runs great now with mech pump pushing 5 psi.:thumbup:

ssmonty & PatM,
Thanks so much for all your input. I've learned a bunch reading these forums over time so I decided to join. Hope to 'talk' with you all soon.:D

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