Quick Fuel 600 Carb, excessive accelerator pump arm lever play?

[KnightNight]

I am getting some off idle hesitation under heavy throttle which I believe is due to the accelerator pump not engaging properly.

I checked the instructions for how to adjust the spring but my accelerator arm lever has no pressure to apply upwards. The carb is new and I checked the diaphragm and saw no cracks/tears/rips.

Any suggestions. If I remove the slack between the arm and the throttle cam lever, the pump is close to bottom out already. The accelerator arm basically doesn't push back.

 

[KnightNight]

Edit: Figured it out, the diaphragm is missing the internal return spring from the factory...

 

[alldodge]

Good deal
Don't know of any using the quick fuel carb here at iboats, there are several using them on OSO

 

[KnightNight]

Mine is basically a Holley 4160 with a little more tuner friendly features. Pretty sure Holley bought out quick fuel back in 2013.

 

[Lou C]

I don't think Holley's quality control is particularly good. I had a problem with a brand new 4160 that I eventually traced to loose clutch bolts on the secondary metering plate.

 

[KnightNight]

Basically what happens when Holley is basically a monopoly on the carb market. Overall though I am happy with my quickfuel (I know Holley owns them). I do wish it had a fuel dump vent hookup on the carb itself. Almost all marine fuel pumps have a dump tube to the carb if the primary fuel pump diaphragm ruptures to alert you of an issue and not dump fuel into the bilge. This quick fuel carb was supposed to be a marine carb (basically they just painted it with rust inhibitor paint, a few stainless parts, and some j-tubes) but not really fully marine adapted it seems. Have to instead run a dump to the flame arrestor.

Doesn't make since why my marine carb has two timed spark plug ports and a manifold vacuum port when barely anything is run off vacuum in a marine environment. Most boats don't even run vacuum advance because boats are under constant load. They could have easily made one of those ports a fuel dump port if it was truly adapted to marine environment but that would require all new body designs/etc.

 

[Lou C]

That never made sense to me because the Holley branded marine carbs all have the nipple on the air horn for the pump overflow hose….
I actually prefer the Quadrajet it’s a more efficient carb than either the Holley or Edelbrock

 

[KnightNight]

That never made sense to me because the Holley branded marine carbs all have the nipple on the air horn for the pump overflow hose….
I actually prefer the Quadrajet it’s a more efficient carb than either the Holley or Edelbrock

The Holley marine 4160 600 CFM Holley only has one nipple near the air horn (which might just be for PCV/manifold only)

Holley 0-80319-2 600 CFM Marine Carburetor

All Holley Marine Carburetors are designed to meet Coast Guard specifications. A marine carburetors fuel metering system is calibrated to compensate for unique engine loads found on boats. The J-style vent tubes direct fuel/fumes back into the carburetor for safe operation while on rough...

www.holley.com

The quick fuel 4160 600CFM has 4 ports, one in the rear for PCV, two timed spark ports, and one manifold port just like the street Holley 4160.

Quick Fuel M-600 M-Series 600CFM Marine Carburetor

QFT brings its engineering expertise to the marine market. The M-Series feature billet-style metering blocks and throttle bodies for more precise performance and exceptional strength. •Exclusive Black Diamond coating for enhanced corrosion protection and appearance, coating provides a 6%...

www.holley.com

Holley 0-80457S 600 CFM Street Warrior Model 4160® Carburetor

Holley has been the world leader in carburetors for over 100 years. We are proud to announce the newest member of our carburetor family- the Street Warrior. The goal in designing the Street Warrior was to take all of those years of experience and build the ultimate performance street carburetor...

www.holley.com

All strange for so called marine carbs. Market is probably small so they rather just slap some paint, few stainless steel/alumnium parts, pop in some j-tubes, and up the jet sizes over the street ones and call it marine. Not a deal killer as I bought a vent nipple for my flame arrestor which works fine. I just had to poke a hole in it...