I am assuming you have a stock mechanical fuel pump.

First, ditch the regulator.  Permanently.  You do not need it.  Then verify the float level is set correctly.

Then, check the vent on your fuel tank to see if possibly the hole is clogged causing the tank to build a vacuum on the system as it cools off after driving.

Be sure your hard line from the pump to the carb is not touching anything that could get it hot, causing an expanding bubble to push fuel back.  Also check hard line under the car for possible heat source nearby.

Just suggestions, nothing concrete, but maybe this will get you heading in the right direction.  If it was a Holley, I would suspect the accelerator pump leaking.  Edelbrock should not have anything external to leak.

My Edelbroke does the same think only  more days to drain down.
I THINK its the needle/seat leaking.....letting the fuel drain out of the carb.
Pull the top of the carb and have-a-look(easy enough to do)
May be just a leaky gasket/o ring OR....have a can of carb cleaner/Brakleen(I love that stuff!) handy all the time.
If its like mine......a good squirt down the throat(no pun!) a couple of times  will get it fired right up(again no pun!)
Let me know what you find Tag!
6s6

6sally6 wrote:

My Edelbroke does the same think only  more days to drain down.
I THINK its the needle/seat leaking.....letting the fuel drain out of the carb.
Pull the top of the carb and have-a-look(easy enough to do)
May be just a leaky gasket/o ring OR....have a can of carb cleaner/Brakleen(I love that stuff!) handy all the time.
If its like mine......a good squirt down the throat(no pun!) a couple of times  will get it fired right up(again no pun!)
Let me know what you find Tag!
6s6

every Edelbrock carb I ever used did the same thing when it sets for a while.  I have replaced them with a Holley and they set for a month or so and start up right away.  On some vehicles with a Edelbrock, I use electric fuel pumps with a primer switch to fill the bowl prior to start.  Otherwise, keep a squirt bottle with gas and give it a couple squirts prior to starting.  Jery
 

boomyal wrote:

My OEM 2bbl 2100 Autolite does the same thing.  Maybe 3-5 days for it to occur.  I have often thought of rigging an electric booster pump that I could switch on for a few seconds before attempting to start.  Haven't gotten around to it yet.

 
Someone posted about six months ago about building a hybrid fuel pump system to do just that. I did a quick search and could not find it. A timeout relay and a check valve should be all you need. Plumb both electric and manual fuel pumps in parallel with the check valve downstream of the electric pump. A cheap, low pressure electric fuel pump is $10-20.

My Edelbrock 1406 can sit for two days or two months and it lights right off. I have a phenolic 1" spacer under the carb. I have a stock fuel pump. 

MS wrote:

All that stuff about secondary pumps seems a little ridiculous to me.  There is probably a check valve in the mechanical fuel pump that is not seating.  A $20 new pump from OReilly will cure it if that is the problem.

As much as I seem to fall victim to it sometimes, it just makes no sense to add parts to a car to bandaid a problem instead of just fixing the problem.

The cars did not have fancy spacers or extra fuel pumps before and ran just perfect.  I had an Edelbrock 600CFM on the 302 in my truck.  It did not even have a choke on it, but could sit for a month and fire right up and run perfect whenever the key was turned.  I do not think there is an inherent problem with the parts you have.  There is just A problem with one of them.

Amen!

I would leave the regulator off as it is just extra weight to carry around and something that can add complexity.  Since you have narrowed down the problem, I would start with a float adjustment and new needle/seat so you are sure the carb seals.  If that does not cure it, start working upstream to the pump.

You probably just have some dirt or crud on the needle/seat or it has deteriorated over time.  Or, if a new needle/seat breaks the budget, remove the old one and clean it.

If this is the AFB or AVS type (Carter) Eddy, the body design is such that the only way it can leak is if the casting is porous. The lowest level it could drain down to would be to the level of the gasket(s) for the venturi cluster (if the gasket there was leaking), there are no gaskets (fuel related) that are lower than that point. The next thing that could drain the carb would be if the air bleed(s) were plugged, siphoning the bowl(s) dry when the engine is shut off. If this is a ThermoQuad type Eddy then you could have bowl leakage, but few people run these. Either way, with a properly dialed in choke (and everything else being good!), your car should start and run even if your pump isn't pumping up fuel at first.

An example is when my car is cold I can pump the pedal a few times, set the choke on the last stroke (manual) and start it without powering up the fuel pump (separate switch). It will immediately fire up and run for about 20-30 seconds before it drains the bowls and stalls, which makes sense with a carb with fuel still in it. Just something to consider in the pursuit of your problem.

Good luck!

ETA: You could take the top off of the carb and check the fuel level in the bowls over a couple of days to see if they lose anything (drop the cover back on to slow evaporation). Other than that the problem has to be elsewhere. In the day Carter advertised the AFB/AVS as having no gaskets below fuel level, unlike their competitor , so no leaks.

Last edited by 351MooseStang (9/14/2016 12:06 AM)

Follow up on my 68 repair involving a new fuel pump.  The car sat from Friday to Monday and started as soon as I touched the key.  I am thinking the fuel pump was not holding gas up and it was being siphoned back down to the pump.

Let us know what cures yours!

351MooseStang wrote:

Not saying that you're wrong, Steve, or that your fuel pump wasn't bad, but your carburetor is still full of fuel from when you shut it off. At least it should be! One note is that I run ethanol-free gas and live in a cooler climate so I don't have fuel evaporation issues on hot shutdown. I don't know if people running ethanol blends are having that issue bit it's a possibility (I've read of it).. Either way, as long as that carb is full of gas when you go to stroke it to set the choke, it should light right up when you hit it (all things being right). It'll die shortly thereafter if fuel isn't pumped up to the carb.

It's interesting that you did see that result though.

Totally agree with that.  Theoretically the carb bowl should stay full of gas.   Only thing I could figure is the pump might be having some kind of siphon action on the carb if it starts backflowing.  This is one of those things I really want to take to the next level and disassemble the pump and carb (that I took off) to see how all the check valves/needle & seat work in this particular application.  Only after doing that can I put together some logic for exactly what is going on.  Just need that spare time & round tuit to be able to do that.