The fuel magically disappears from my carb!

[moparedtn]

The 850 Demon in my 440/493 Charger can sit for weeks and still start up fine. THIS is even with the California blend of pump gas. NO spacer, NO electric pump.
The Holley 600 in my 75 Power Wagon can also sit for weeks and still start fine. Neither has a functioning choke either.
I had a 73 Dart Sport 340 with a ThermoQuad. It was hard to start when cold or after sitting a few days. I blamed the problem on the accelerator pump....BUT once I attached a proper choke to it, it started up easy even after a month of sitting. No ****, I was shocked! For years I have bitched about ThermoQuads being a POS carb but maybe I was to blame the whole time!

I do think there may be something to the Carter/Eddy carbs being more susceptible to the problem than the Holley design based carbs are.
Never had this issue with the old 3310's I used to run - but then, the gas was different back then (no ethanol), too.

 

[miller]

Strange...no body mentioned, could be the seats/needles leaking.

 

[moparedtn]

Strange...no body mentioned, could be the seats/needles leaking.

I did actually think of that. They're new in this carb, but if that were happening, how would it manifest itself? Fuel would be ponding in the intake?
Plugs fouling or sooty black?

 

[JimKueneman]

Live with it or get a loud *** electric fuel pump. I have Edelbrocks on two cars, both run great. One has an electric pump and one has a mechanicsl. The electric pump starts on the first turn. The other, well, it does not.

Even FI may not fix it. My Go-Street take exactly 4 turns to start after sitting a few days. No more no less and I can't make it change. It is not fuel pressure. Once it starts once it will start on a 1/2 crank every time after that. Some others with the FiTech see the same thing.

 

[miller]

I did actually think of that.

Gas would bleed down, past open valves, into the oil pan...if enough. Pull the oil stick, and smell for gas.
The float seats take a gasket, if that helps. Just thinking out loud.

 

[Ranger16]

Wait a minute. Look at the carb diagram. If I am reading it correctly, the fuel passage from the metering rod/jet has to be drawn UP into the venturi. The fuel passage is much like a trap in a sink drain, which should rule out a leaky metering rod/jet. It can't leak down via the jets.

That said, I've recently had the same hard starts, but attributed it to ignition. My car has not been started in just over a week (same carb). I'm going out to check the float bowl and will report back.

 

[Bruzilla]

I never could figure out the why's of my fuel flow problem so I finally put a Mr. Gasket electric fuel pump on the car - the problem was magically resolved and has yet to reappear.

That's not really magic. An electric fuel pump spins up as soon as the ignition turns on and takes about a second to get gas to the carb. A manual pump doesn't do anything until the motor actually starts cranking.

 

[eldubb440]

unless the float is stuck or fuel is boiling, edelbrocks are a leak proof design..... I would think most of the evaporation occurs after shut down while the engine is still hot

 

[Bruzilla]

How did I know this was a post about an Edelbrock carb as soon as I read the title?

 

[eldubb440]

How did I know this was a post about an Edelbrock carb as soon as I read the title?

I believe it's more about the fuel

 

[Ranger16]

The results are in.
I pulled a metering rod and it was bone dry. I then held the choke open and looked down in there with a flashlight while working the throttle. The first time I saw the accelerator pump squirt fuel so I doubted my finding, but the second time it sputtered a bit and by the third pump, it was dry.

So I know it will evaporate in a week (faster than I had expected). The question now is how many days does it take for the bowl to go dry?

Next time I'm going to swing the metering rod cover open and prime the bowl to see if that makes it start quicker. I suspect it will. The funny thing is, I don't recall this being a problem earlier in the year, or even last year.

EDIT:
I decided not to wait for the "next time". I used a plastice bottle with a nozzle (the kind you'd use for olive oil), filled it with gas and squirted about 1/4 - 1/3 of it down the metering rod hole. Put the cover back on the metering rod and cranked her over. She came to life in an instant.

 

[TxDon]

I had and still have the same issue with my car although it is much improved. When I first got it was so poorly tuned it barely ran, stinking rich smell, overheated fuel percolation plus evaporation emptied the carb when shut off. After fixing float level, jetting, metering rods, adding phenolic spacer, changing timing and fixing the cooling system, much better. No more oil contamination or percolating but evaporation from ethanol still an issue. If it sits more than 3 days it needs some crank time.

 

[PP1RT]

I do think there may be something to the Carter/Eddy carbs being more susceptible to the problem than the Holley design based carbs are.
Never had this issue with the old 3310's I used to run - but then, the gas was different back then (no ethanol), too.

And it helps with the Holley having the fuel bowls out on the ends and not inside the carb.

 

[PP1RT]

What happens if you mix in some race gas? Does that make it better?

So if the gas is evaporating from the carb how does the fuel line empty enough to make it so you have to grind on the starter to get it primed again?
I am trying to learn too.

 

[coloradodave]

Even FI may not fix it. My Go-Street take exactly 4 turns to start after sitting a few days. No more no less and I can't make it change. It is not fuel pressure. Once it starts once it will start on a 1/2 crank every time after that. Some others with the FiTech see the same thing.

This is fixable. Increase the initial fuel shot in the coldest setting, or cycle the key on/off twice instead of once when cold.

 

[oldbee]

What happens if you mix in some race gas? Does that make it better?

So if the gas is evaporating from the carb how does the fuel line empty enough to make it so you have to grind on the starter to get it primed again?
I am trying to learn too.

Fuels probably still in lines but you need a couple fuel pump cycles to refill the float bowls, then fuel has to run thru passage to acc.pump cavity before you get a shot from throttle movement. Plus the first thing to evaporate is the "light end" of gas that is the easiest part to explode.

 

[JimKueneman]

How did I know this was a post about an Edelbrock carb as soon as I read the title?

Oops wrong thread!

 

[miller]

Wait a minute. Look at the carb diagram. If I am reading it correctly, the fuel passage from the metering rod/jet has to be drawn UP into the venturi. The fuel passage is much like a trap in a sink drain, which should rule out a leaky metering rod/jet. It can't leak down via the jets.

Yeah, your right Ranger16. Shouldn't 'leak' down via the jets, until a vacuum comes into play.
Leaking float seats/valves will flood the carb, and float settings will, if too low, dry out the bowls, too high, overfill them.
Been awhile since I've thought about all this stuff!

 

[coloradodave]

How did I know this was a post about an Edelbrock carb as soon as I read the title?

We get it, Bruzilla! You don't like Edelbrock carburetors! It's not news anymore, but it is still just an opinion, and you know what they say about opinions...

 

[1967coronet]

Ed, we got ya covered old buddy