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4/28/14 12:42pm - Original Message: 'Carb loses fuel when sitting over night. Hmmm....venting issue?'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
As I'm chasing down my low fuel gremlins I've kinda noticed the shop smells like fuel more than it should after the car sits right after driving. Issue: the carb bowl loses fuel when sitting. After 24 hours or more I have to crank the engine a number of times to refill the bowl before it fires. I have an Edlebrock reproduction Q jet. I need to look at the fuel inlet to see if the fuel can be sucked back out by an improperly vented tank. There is that tiny fuel filter int eh carb inlet that has a one way valve in it. It seems to be working. That would nuke the tank venting issue I would think. There is a return line on the fuel pump I need to chase down...or is that some other kind of emissions line?
Thoughts?

How does our tank vent? Through the cap? One way valve on top of the tank? I need to look into the carb body to see if there is anyway it can be dripping into the intake when sitting but these 1 piece Q-jets don't have any gasketed parts below the fuel line.....I dunno...

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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4/28/14 12:47pm - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
HighDesertDave said:... these 1 piece Q-jets don't have any gasketed parts below the fuel line.....I dunno...


One piece Q-jet?!?! It doesn't have a separate throttle plate? On a "normal" Quad, the main reason for fuel loss like that is the lead core plugs in the carb bowl. They get loose, and leak the bowl dry overnight. The fix is to disassemble and tap/peen the core plugs in tighter with a small hammer...then seal them with JB weld....


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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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4/28/14 1:09pm - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
1 piece meaning no fuel bowl gaskets like the holly's. Ya I've looked at those plugs before. Guess even on a new carb they could leak. I think the fuel inlet is too high to suck the bowl dry anyway...killing my improperly vented tank theory. Guess the carb will come off...again. Hey better than trying to mess with the gas tank si?

Thanks,
Dave

____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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4/28/14 1:34pm - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Never trust those plugs...new or not. Don't depend on those stoopid little foam pads that come in overhaul kits, either...those things are useless. Angry
Those plugs are in the bottom of the fuel bowl, so if they leak, the fuel will disappear down into the intake....and then ya gotta crank and crank to fill the bowl again.
Not likely to be siphoning back thru the inlet, either, UNLESS the carb is boiling the fuel after you shut it down. That raises the level in the bowl....which should raise the float, and seat the seat even tighter. BUT...fuel vapor will not hold the float up to seal. Even then, tho, there should be enough fuel in the bottom of the bowl to fire it up, at least. If the plugs leak, the dang bowl will be dry....you might get a small squirt out of the pump, but not enough to fire it off.

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Joel Adams
C3VR Lifetime Member #56    
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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4/28/14 1:48pm - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
And a small pitifull squiret is all she gets after sitting 24 hours or more. Ok, money is on the base plugs. Guess I'll check the float level while I'm it. Maybe pull the jets and needles and write down what they are. Like I have nothing else to work on on this car..... LOL! Thanks for the info....

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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4/29/14 2:05pm - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
JohnRR
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Joined: 2/22/2011
Posts: 110
HighDesertDave said:  Like I have nothing else to work on on this car.....

It's not just a car, it's an adventure!

Pretty much everything on mine has been on and off several times until I get it right.  

Enjoy the ride,
John



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1973 BB 4-Speed Coupe Project Car
2009 Z06 Mostly Stock
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4/30/14 5:36am - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
dyoes
Former Member
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Zachary, LA - USA

Vette(s):
1974 L-48 Auto. Just your basic Vette. GM crate motor w/vortec heads and intake. Crane cam. Scorpion rockers, Edelbrock carb. Lots of parts still in boxes... :(

Joined: 1/27/2013
Posts: 201
HighDesertDave said: Like I have nothing else to work on on this car..... 

There is nothing like buying a $15,000 car, tearing it down so it's worth about $5,000, sinking $20,000 into it, and having it be worth $17,500.  Welcome to the world of Corvette ownership.  Confused


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"Let them that don't want none have memories of not gettin' any."
- Brother Dave Gardner

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4/30/14 10:41am - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
jdgrant Gold Member
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HOT SPRINGS NATIONAL PARK, AR - USA

Vette(s):
1978 (25th Annv. Edition)Red, Black interior, 4-Speed Transmission, L-82, Power & Air, Very Rare Option Package(Only 145 Red 1978s with a 4 speed trans) & Very Original Car, with original Window Sticker, Bill of Sale and all documentaion.

Joined: 11/12/2003
Posts: 190

AMEN!Ouch



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John D. Grant "Corvette; Cure for the common mid-life crisis!"
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5/1/14 12:53am - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
dyoes said:
HighDesertDave said: Like I have nothing else to work on on this car..... 

There is nothing like buying a $15,000 car, tearing it down so it's worth about $5,000, sinking $20,000 into it, and having it be worth $17,500.  Welcome to the world of Corvette ownership.  Confused


Now THAT is funny! In a sweet and sour kinda way. Like the L88 hood I couldn't pass up that needs to be paint matched....or $900 leather seat covers I just ordered....or.....but it will be sooooo cool! Wacko


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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

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5/6/14 1:25am - Reply: 'Re: Carb loses fuel when sitting over night. Hmmm....venting issue?'
HighDesertDave
Former Member
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Carson City, NV - USA

Vette(s):
Numbers matching 1972 350 4 speed, silver pewter body with blue interior

Joined: 12/4/2013
Posts: 239
Pulled the carb, propped it up in a clean oil drain pan, filled with gas and.....watched the fuel seep out of the throttle shafts which is the path of choice from those leaky fuel bowl plugs. Did I mention this is a new Edelbrock carb? So got into it, tapped the plugs in nice and tight and decided not to use the JB weld I bought. I saw pics online showing how it breaks down over a few weeks and turns into a yellow gooey caramel mess. I refilled the carb, let her sit for a while, no leaks, reinstalled. Went to fire the car, it lit and died, the carb was over filled with fuel which then overflowed onto the intake etc. Flooded the engine.....so I pulled the top off, popped the stuck float loose (would you believe the shape of the float, if allowed to sink to the bottom of the bowl, will wedge itself down there? Like we NEVER run out of gas...), reassembled, fired, drove. The garage didn't smell of raw fuel last night like it used too although my sense of smell was shot yesterday....I wreaked of gas for hours. Guess its fixed. I'll try and start her in a couple days and that will tell the tale.
Funny, a few engine issues are now making sense...as in when I'd pull up into my driveway which is angled up a bit, the car might die...which was always fuel starvation....I suspect the leak was so bad, at the slight angle, the idle jets were starved of fuel. I've had a hot hot starts that seemed like she had flooded...which now makes sense...all that dripping fluid was washing into the manifold while sitting. And the big clue, there are orange stains on the floor of the intake....drying puddles of raw gas. I have a 73 Chevy C20 with most of these symptoms....guess what I get to do?....call me The Carb Masta'! (or not Ouch )




|UPDATED|5/5/2014 11:25:37 PM (AZT)|/UPDATED|


____________________________________
My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

 Reply Reply  Quote Reply w/Quote
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