My Vette (76 - L48, 4spd, Stock, Qjet) always needs about 10-12 pumps of the pedal to get started, after sitting more than a day or two.

Is this just the nature of the beast or is a carb rebuild in it's future? Once started, it runs great, choke works as normal and then will idle smooth, etc. Warm starts are not a problem.

We seem to be getting closer to the "off season" every day and was thinking "might as well" add this to the list.

Thanks

 

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Sounds like a common Q-Jet problem. There are lead plugs at the bottom of the fuel bowl, they have a tendency of leaking while sitting for a day or so. If you are going to rebuild your Q-jet, use a 2 part epoxy and coat the lead plugs. This helps with the leak down problem.

Plus it seems that your accelerator pump may be a little worn since you have to pump the heck out of it.

Before you go rebuilding you carb, check the primary (front) throttle shaft for excessive play. Grasp the throttle linkage and try to move it front to back/ up and down. If there is slop in there, the throttle shaft is worn, this will cause a vacuum leak which is common to Q-Jets. This problem requires some drilling and bushings installed to make a rebuild work properly. There are kits available for that problem.

Let us know what you find

Sarge

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

Good info from Sarge.  But don't overlook the simple.  Is the choke plate closing when cold?

Thanks Sarge and Ken for your responses. I have a carb book by Doug Roe and saw a picture of the plugs you are referring to.

Does that fuel leak into the throtle body or out through the gasket? I have never seen what appears to be a leak around the gasket.

I'm still trying to figure out how a carb is supposed to work. With Doug Roe's book, and the the write up that Ken did - I seem to comprehend a bit more each time I go through it, but those first two or three attempts were very discouraging to say the least. 

I still plan to rebuild it myself, but I need to get my confidence level up just a bit more. 

Thanks again -

 

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Something else to consider...besides what has already been said regarding the carburetor, gasoline today is blended primarily for fuel injected cars and evaporates quicker than the gas available when our cars were built, resulting in the need to crank the engine and pump the pedal more to get fuel into the carb to begin with. If your carb has any problems, this just aggravates the situation.

Typically the fuel that leaks drops down on the throttle and into the intake.  It slowly evaporates from there leaving no trace.  Due to the air cleaner you normally won't even notice a smell.

Yes, I've tried just about everything I can regarding the hard starting of my '76, including the 'well plugs'.

I've decided it is the loss of the anti-evaporation additive in modern fuels that is causing it. 

Oh well, just keep cranking.

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New fuel pump in recent history?

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Alas yes, last year, didn't make any difference.

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It's not blended "for fuel injected" cars.  It's blended for the EPA and their stupid regs.

My Holley carb doesn't have this problem. Starts right up after sitting for a month.

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Mine is a few cranks quicker.. 

Set the choke for a cold start, turn the key, crank the engine while pumping the gas and stop after 5 seconds. ( I "imagine" the fumes slowly traveling down the intake to the heads).  Turn the key, crank and give it a little gas and it fires off.   The sequence is no different if I crank it for 20 seconds.  Mine demands a pause and fires off at "round two"

The choke sets fine and OEM coil spring pulls it off perfect as it warms.

This is the best mine gets!   I've had the Quadrajet rebushed and plugs epoxied. A new fuel pump might have cut a second or two off the cranking.  It's been like this for 30 yrs so I'm at peace with it.

 

 

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I'll try the two crank start.

Mine has only been like this for about ten years.

That is why I think it is the deletion of anti-evaporation additives in fuel.

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Surprising followup:  My C3 has sat for 6.5 months.  I turned the key and it fired off on the 3-4 rotation of the engine!

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Or, you could get one of these.🤡

But seriously Willis, I agree with those here who bitch about the fuel. It's a power-robbin' jet-pluggin' blend that's here to stay. I've got your same problem with the carburetor on my '80 Toyota 4x4. I am sentenced to carb rebuilds much too frequently, just in order to pass this state's smog test. The Rochester I had on before was prone to being "dry" after just a couple of days sitting. I now now where the fuel was going, thanks to responders above.

Good luck on the fix.

Steve

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