waterplay

This one has me stumped! The carb is a Quick Fuel 750 annular discharge. I have an issue with fuel shooting out my Holley style carbs vent tubes. This should be an easy fix you would think but so far it has me and others stumped. Things to keep in mind… The car was running and driving fine then I parked it for about two weeks.
What I have
1. Quick Fuel 750 Annular (Holley)
2. Brass float in the front composite in the rear.
3. Electric Holley Red fuel pump

This is what I have done and some observations.
1. I tried to set the floats several times to the point that now they are set at the lowest possible setting and still the fuel fills the bowl and just keeps going. I have sight glass fuel bowls so I can see the fuel level in the bowl.
2. I replaced the needle and seat two times thinking it was a bad seat or even a defective O-ring
3. Dissembled the whole carb twice and replaced all the gaskets.
4. Replaced the fuel bowls with new ones thinking the O ring on the needle and seat were not setting properly.
5. I took the bowls off and blew through the fuel inlet side and made sure that when I raised the float the flow of air would stop. It did and should be ok but I still have the same issue.
6. Replaced the floats
7. Checked the floats to make sure they are not saturated. They all tested ok.
8. Fuel pressure was over 9 originally but I am not sure what it was because I did not have a gauge on it at that time.
9. Installed a pressure regulator with a fuel gauge. Pressure read around 9 psi. Adjusted pressure to 4.5-5 psi. It continues to creep up to closer to 6psi even after several re-sets to the regulator.

So far I had most of the parts at the house or I was able to borrow from a friend for testing so the cost has been minimal. I don’t want to just go out and start buying replacement items just to test. Does anyone know what could be wrong our ever experienced this same issue?

Matt Gruber

if i had it i'd hook up my gravity feed for a test.
sounds like fuel PSI is too high, get it down to 1-3 to test, raise it if it works ok

weimer20

I had the same prob with my Holley at one point. It turned out to be a stuck needle valve on the float. Being that it sounds like you checked that possibility very completely, I'm at a loss for an answer.

ltlevil

Did it continue to spew after you adjusted the pressure to 4.5? Sure sounds like the internal regulator in the pump went bad. You didn't say what type of regulator you got but if is a cheep one (spectre) that comes with a gauge you have to get three to get one that the gauge and regualtor both work-ask me how i know

ltlevil

bwellisley

i've posted about my similar problem a few times...i also checked all parts of the carb and i'm now leaning to it being too high on fuel psi. my issue arrises after the car has been running for about 1/2hr, and thereafter when the engine is at temp. seems to work fine when cold and after pressure has been released.

any suggestions for a regulator?

i have a 327/350 with mech pump to a fuel filter to the chrome dual line feed to the 650 holley carb. i'm thinking i'd have to make a bracket to hold it and place it between the fuel filter and the dual line feed to the carb...?

waterplay

The fuel still shoots out even at 6psi. The reg is the Holley one. I would think the pressure should now be ok at 6psi. The amount of fuel comming out is less than before. Without the reg it would shoot up about 6-8in. with reg only about 1/4in. I have a match and may use it.

Matt Gruber

6 psi is too high 2- 4 is fine for street use.
use 12-804 $27

lars

I'd run the Mallory return-style regulator and get that fuel pressure down to 4 psi max.

AndreG

Are you setting the pressure with a liquid filled fuel gauge under the hood? They suck! As soon as the fluid gets warm the gauge indicates a pressure drop and continues until it reads almost zero. Trying to set mine after the car was runnng for just a couple minutes ended up giving me way too much pressure. The gauge was mounted on the fuels line above the manifiold and never felt like it was getting very hot. I put in a cheapo non liquid filled and I was able to more accurately set the pressure and see wat was going on. You really don't necessarily need that much pressure. I would set it to a few pounds, set the float levels right and only if you starve for fuel turn it up a little at a time. Otherwise it can be a very quick way to burn you car flat to the ground.

Hope that helps
-Andre

waterplay

Not to question you but I am confused. Holley recommends 4-7psi. Not sure if 2-3 will be enough. I ran about 7psi in my old car without any issues but I ran it high on purpose because I would sometimes run Nitrous. The 12-804 looks like what I have but I am not sure of p/n.

waterplay

Lars,
U-DA-MAN so I will try that. I do not have a return on the car. When I ran the 8an line I dropped using the return. You are the second person that recommended running the return line. Also with my setup will 4psi be enough? I will be running it both on the street and in NASA road course events. I was thinking 6psi but if you say 4psi than ok.

AndreG
The gauge is the liquid filled style but I have not started the car yet because the fuel shooting out. I have all the plugs pulled to let the engine air out from all the fuel in it. And an oil change is next after I get the fuel issue done.

Matt Gruber

return line will really help keep the carb cool on a road course.
reg w/return is better if u dont mind the cost.
or run return thru .060" jet, before it enters 12-804 reg for low buck fix

norvalwilhelm

Why 4 max??? I thougth 5 or 6 pounds is right for the street? I have both my cars regulators set at 6 pound and never had a problem.

He seems to have covered all the bases, floats and needles and seat and still it flows past the needle of both sides??? That is the strange one? One I could understand and start looking for a casting flaw but both??? If you have a friend with a holley could you borrow a float bowl and assembley?? 4 screws and install his float/bowl/ needle seat as a unit and see if the problem is solved?
I did that and it was a casting flaw.
Good luck

norvalwilhelm

I don't agree with the return line. I have run my vet for 20 years without a return line and the mustang for at least 10 again without a return line. The vet has a high dollar regulator set at 6 psi and the mustang has a low dollar holley set at the same 6 and both cars have had flawless fuel system all those years.
NO return line ever.

waterplay

Norval,
I thought the same thing about casting flaws. Step 4 of my 5000 steps was to replace the bowls. I too have run other cars for years without a return line but I will try almost anything at this point.

Matt Gruber

u could cut a hole in the hood and move to canada.
i hope 230 million guys don't chime in MY CAR RUNS FINE
that won't help fix this.
the return line won't fix it; it's just a good idea w/ solid hoods in hot climates

Matt Gruber

did u fix it?
i had this problem today and traced it to a nick in the seat of my 4165

fendiracing

I had similar problem with my alky 4150 holley. I had notched floats (composite) for my jet extentions. I learned after a few times of gas squirting out to turn the carb upside down and then assemble the metering block and float bowl---float was getting a little hung up when dry...........never had a problem after that------------anyways you probably already figured this out---better late then never

fendiracing

waterplay

Ended up that I had too much pressure without a regulator. Although the pump I was using did not need a regulator when working properly. It turns out that trash built up around the internal fuel pump bypass and maxed out the pressure. Cleaned everything from the tank to the carb and the thing started to work ok. Then noticed that I was way to low on pressure. This was because the regulator was set to cut back the original high pressure. I adjusted the regulator and now I have the correct pressure. Next step is to remove the regulator and see if it is still needed. But I did get the car out to the Mid Atlantic Vette Fest (170+ mile round trip) and it performed flawless.

King Lear

Good that you got it fixed, but if you have anymore problems, I have the same Quick Fuel Q-750-AN or SS-750-AN carb you do and had the same problem. I replaced the floats, needle & seats, etc. Turned out I had a cracked fuel bowl. I called Derek at quick fuel and they sent me a new one, I was only coming out the secondary vent tube. Switched the bowl out and that was the fix.