Quadrajet Carb. Questions- call me a traitor!

[manzanita]

OK. Call me a dirty traitor, but I'm having issues with a Rochester Quadrajet carb and this is the best forum for honest expert advice I've ever come across. I used to have an account here, but it's been a few years since I've been at Stangnet. (I still have my pony, though!) If it makes you boys feel any better, the carb's on a chevy 350 block in my boat.

Ok. Now that I've got that out of the way, here's my story:

I have a Rochester Quadrajet that recently started to leak fuel all over the engine. The engine has previously run fine with a few hundred hours on it. Upon inspection, this fuel leakage/overflow is emanating from the point where the accelerator pump piston passes through the top of the carb body. (Please see the blue arrow, and oh yeah, this pic is of a Quadrajet, but I took it from off the net, and it's not a pic of the actual carb in question). This happens 5-10 seconds from startup.

What I've done/tried since the problem began:
1. replaced the accelerator pump (including the rubber "cup") assembly with a new one from a rebuild kit. This did not help.

2. Adjusted the float level in an attempt to limit the amount of fuel entering the fuel bowl. Checked for a "sticking" float. The float appears to be intact and operating correctly.

3. checked needle valve for goop/sludge/etc. that would keep it from closing properly when the fuel float floats "high" because there is already adequate fuel in the bowl for that exact moment.

The engine did sit over winter, but has been started occasionally and run, and this appears to be a new problem, rather than one which has gone on for a while and is just now being noticed.

I'm at my wit's end. I'm scared to death to have free-flowing fuel pooling up on my engine and on top of the intake manifold, spilling down to who knows where.

What am I missing?

Thanks in advance!

 

[D.Hearne]

I can't tell you what's wrong, but if it free flows fuel all over the engine, it's not a certified carb for a marine application. Could get you a ticket if it's ever inspected. Oh, and Ford DID use Quadrajets in a few applications in the early 70's on 351C's and 429/460's.

 

[bnickel]

sounds like the accellerator pump bore is worn and has a groove in it. run your fingernail across the bore and if it catches you have a signifigant ridge. you might be able to smooth the bore with some very fine sandpaper, but more than likely you're going to have to replace the carb. edelbrock makes a decently priced marine certified carb as an FYI

 

[jeff69becky]

I would just recommend getting rid of the carb...Bnickel is right Id go with the edelbrock, I had a quadrajet on a buick I owned never could get it to work right...

 

[krash kendall]

The quadrajets have porous floats in them and sink if there is the minutest hole in them allowing fuel to continue to pump into the accelerator bore. But the motor usually floods out and dies unless you hold the throttle wide open.

 

[bnickel]

qj's are excellent carbs as long as they work right, but when they start having problems, almost always wear related, they're junk. if the the accelerator bore is actually worn badly you'll probably find the throttle shaft bores are worn just as badly and that is an expensive fix, you have to find a carb shop that has the right tools to ream it oversize and install a bushing kit. finding a good carb shop that can actually do it is getting harder to all the time