Quadrajet float bowl leaking down - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DT1 · 07-09-2012, 03:09 PM

I have always had a problem with my Quadrajet leaking down after sitting for more than two days. After I depress the gas pedal to set the choke, I have to crank the starter for at least 5-7 seconds to allow the float bowl to fill. When it finally starts, I get a big puff of rich black smoke for a second.
I sealed the bottom well plugs with Cliff Ruggle's kit but it didn't solve the issue.
Does anyone have any other suggestions to fix the problem. The only thing I can think of is that the float valve isn't seating properly. Maybe the power piston spring is too light?
Any suggestions would be appreciated.

cdowns · 07-09-2012, 04:39 PM

craking a starter for 5-7 seconds has always been normal on the old vehicles i've owned

RustyBucket · 07-09-2012, 06:02 PM

Have you got a good squirt on your accelerator pump?

mMad Dawg · 07-09-2012, 06:28 PM

Just a thought,but did you happen to check your fuel pump ( mechanical ).If the diaphram in them has a slight leak the gas will drain uot of the carb. Usually into the crankcase. Hope this helps Gord

Lee H · 07-09-2012, 09:52 PM

5 - 7 seconds is about right. Try to pump the accelerator as you crank, may knock off a second or two.
Posted via Mobile Device

asolde · 07-09-2012, 10:10 PM

I have to crank 5-6sec before it fires off. I think its either my carb float or my fuel pump. I am changing my pump first Bc I have my engine out right now.

ChevLoRay · 07-09-2012, 10:10 PM

"Leaking down".....you're saying that because of the cranking time. But, you know that the float bowls have a couple of plugs that are prone to leaking over time, right? If so, you will know that it will run rich because fuel will leak into the manifold, and flooding will become more common. It's one of the few things I don't like about Q-Jets, but it wasn't enough to keep me from buying a new one.

With Fuel Injection systems, starting is quicker. So, we tend to judge how well these older non-FI engines start, when they actually do very well.

My '69 350, when cold, required me to pump the pedal to set the choke, then I would bump the key and it would burst to life!

DT1 · 07-10-2012, 09:45 AM

Quote:

Originally Posted by ChevLoRay

"Leaking down".....you're saying that because of the cranking time. But, you know that the float bowls have a couple of plugs that are prone to leaking over time, right? If so, you will know that it will run rich because fuel will leak into the manifold, and flooding will become more common. It's one of the few things I don't like about Q-Jets, but it wasn't enough to keep me from buying a new one.

With Fuel Injection systems, starting is quicker. So, we tend to judge how well these older non-FI engines start, when they actually do very well.

My '69 350, when cold, required me to pump the pedal to set the choke, then I would bump the key and it would burst to life!

I sealed up the plugs on the bottom and can absolutely state that they are not leaking. If the float bowl has fuel in it and everything else is adjusted properly, five to seven seconds is an eternity. If there is enough fuel in the bowl to allow the accelerator pump to give a shot and the choke is properly set the engine should come to life almost immediately. I'm still leaning on the float valve. This weekend I will remove the carburetor and fill the bowl with gas and let it sit on the bench for a day or two just to see if I'm loosing gas through the valve.

Lee H · 07-10-2012, 01:00 PM

Quote:

Originally Posted by DT1

......the accelerator pump to give a shot and the choke is properly set the engine should come to life almost immediately.

Even with all systems tuned and set up properly, with this 40 some odd year old technology, this is not going to happen. It may start a little quicker with HEI but still not "almost immediately".

DT1 · 07-10-2012, 01:04 PM

Quote:

Originally Posted by Lee H

Even with all systems tuned and set up properly, with this 40 some odd year old technology, this is not going to happen. It may start a little quicker with HEI but still not "almost immediately".

With all due respect...Some may not start "Almost immediately" but mine does.

Coley · 07-10-2012, 01:05 PM

Check and ensure that your (carb fittings) fuel filter is the 'check' valve type and not the bronze 'cup' style.
The check valve type helps keep the fuel up in the carb to help facilitate faster start up, particularly on 'cold' starts.
Good luck, Keep us posted.
Coley

GASoline71 · 07-10-2012, 08:04 PM

If you're carb is "leaking down" then I'd take a smell of the engine oil. That fuel will go from the manifold to the cylinders and leak past the rings and end up in the oil pan. If your oil smells like raw fuel... that would be bad.

Gary

DT1 · 07-11-2012, 09:45 AM

Quote:

Originally Posted by Coley

Check and ensure that your (carb fittings) fuel filter is the 'check' valve type and not the bronze 'cup' style.
The check valve type helps keep the fuel up in the carb to help facilitate faster start up, particularly on 'cold' starts.
Good luck, Keep us posted.
Coley

Thanks. I'll check that. I got to thinking and I'm wondering if this has anything to do with the reformulated (Oxygenated) fuel. Just a hunch but maybe it evaporates faster??

68gmsee · 07-11-2012, 02:10 PM

Check or replace the needle valve and seat. Even if it's new it can still leak. That's what keeps fuel in the bowl from seeping back to the pump.

So.Cal.Super · 07-11-2012, 02:30 PM

Quote:

Originally Posted by DT1

Thanks. I'll check that. I got to thinking and I'm wondering if this has anything to do with the reformulated (Oxygenated) fuel. Just a hunch but maybe it evaporates faster??

not sure if it does, , I had mine rebuilt and tuned before I installed it. The P/O had too small of an edelbrock on it that wasn't working right. but mine would start the same after a few days or a week.

Key on, electric choke, two pumps and with in 2 seconds it would fire up.

I think I cut it down to 1 after I installed the H/T starter.

07-09-2012, 03:09 PM	#1
DT1 Registered User Join Date: Oct 2009 Location: Gardnerville Nv No Mo Cali!! Posts: 869	Quadrajet float bowl leaking down I have always had a problem with my Quadrajet leaking down after sitting for more than two days. After I depress the gas pedal to set the choke, I have to crank the starter for at least 5-7 seconds to allow the float bowl to fill. When it finally starts, I get a big puff of rich black smoke for a second. I sealed the bottom well plugs with Cliff Ruggle's kit but it didn't solve the issue. Does anyone have any other suggestions to fix the problem. The only thing I can think of is that the float valve isn't seating properly. Maybe the power piston spring is too light? Any suggestions would be appreciated.

07-09-2012, 04:39 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Quadrajet float bowl leaking down craking a starter for 5-7 seconds has always been normal on the old vehicles i've owned __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

07-09-2012, 06:02 PM	#3
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,050	Re: Quadrajet float bowl leaking down Have you got a good squirt on your accelerator pump? __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!! Last edited by RustyBucket; 07-09-2012 at 06:07 PM. Reason: typo

07-09-2012, 06:28 PM	#4
mMad Dawg Registered User Join Date: Jun 2009 Location: Calgary AB. Posts: 88	Re: Quadrajet float bowl leaking down Just a thought,but did you happen to check your fuel pump ( mechanical ).If the diaphram in them has a slight leak the gas will drain uot of the carb. Usually into the crankcase. Hope this helps Gord

07-09-2012, 09:52 PM	#5
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: Quadrajet float bowl leaking down 5 - 7 seconds is about right. Try to pump the accelerator as you crank, may knock off a second or two. Posted via Mobile Device __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

07-09-2012, 10:10 PM	#6
asolde Registered User Join Date: Apr 2012 Location: Henderson Nevada Posts: 804	Re: Quadrajet float bowl leaking down I have to crank 5-6sec before it fires off. I think its either my carb float or my fuel pump. I am changing my pump first Bc I have my engine out right now.

07-09-2012, 10:10 PM	#7
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Quadrajet float bowl leaking down "Leaking down".....you're saying that because of the cranking time. But, you know that the float bowls have a couple of plugs that are prone to leaking over time, right? If so, you will know that it will run rich because fuel will leak into the manifold, and flooding will become more common. It's one of the few things I don't like about Q-Jets, but it wasn't enough to keep me from buying a new one. With Fuel Injection systems, starting is quicker. So, we tend to judge how well these older non-FI engines start, when they actually do very well. My '69 350, when cold, required me to pump the pedal to set the choke, then I would bump the key and it would burst to life! __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-10-2012, 01:05 PM	#11
Coley Registered User Join Date: Oct 2011 Location: Victoria, B.C Posts: 3,794	Re: Quadrajet float bowl leaking down Check and ensure that your (carb fittings) fuel filter is the 'check' valve type and not the bronze 'cup' style. The check valve type helps keep the fuel up in the carb to help facilitate faster start up, particularly on 'cold' starts. Good luck, Keep us posted. Coley __________________ ....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500

07-11-2012, 02:10 PM	#14
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Quadrajet float bowl leaking down Check or replace the needle valve and seat. Even if it's new it can still leak. That's what keeps fuel in the bowl from seeping back to the pump. __________________ 68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive...



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