Carb/Fuel line 'looses prime" takes forever to crank & start after sitting

[AKcharger]

On my '72 if the car sits more than a day the fuel bowls are empty and it takes about 3 min worth of cranking to get it to start.  now after it starts and has fuel in the system it is fine, starts right up. if it sits over night same thing.

So what ON ORDER OF LIKELY HOOD is the cause? no sign of fuel leaking anywhere

400 -  Edelbrock 750, 3 years old

Thanks!

[Kern Dog]

This is common in the Summer due to rapid evaporation but in the cold months? Hmmm.....
Rick Ehrenberg suggested a test: Pour some gasoline into a shot glass, mark the level with a Sharpie and place it underhood near the carburetor. Do this after having the engine up to temp....then come back a day later. See how much gas evaporated from the open shot glass. If the level hasn't changed much, the problem is not evaporation.
If you have a functioning choke, does it help to use Ether?

[AKcharger]

Good suggestion but I've replaced the intake gasket with that "valley pan" to aboid heat, have a "cool carb" plate on it and I found evaporation after it's been running a while and engine is hot...it never does that (well not after cool carb mod and such)

yes ether or a bit of gas in car and it fires right up and runs fine

[Kern Dog]

I had a 360 in a Dart with a rebuilt Thermoquad. Once up to temp, it started easily and ran great. When it was cold.... crank...crank...crank...
I hooked up the choke and son of a gun....It fired up almost instantly every time. I've never been a factory stock type of guy. I've had Holleys for the most part.

[birdsandbees]

Check valve in pump stuck open and fuel is draining back to the tank.

Pull the line off at the carb and see if you can blow the fuel back towards the tank.

[INTMD8]

Check valve in pump stuck open and fuel is draining back to the tank.

Pull the line off at the carb and see if you can blow the fuel back towards the tank.

If the inlet check valve in the pump was stuck open would it move any fuel to the carb?

[birdsandbees]

Yes...

[AKcharger]

Great info guys thanks!

Kerndog- yup has a choke, and seems to be working but when I pop the air cleaner and pump the linkage nothing come out

Birdbee- that sounds exactly like the problem! I'll try that tomorrow!!

[INTMD8]

Yes...

I see,  yeah that doesn't look like it would help

[AKcharger]

Well it is the carb...When I disconnected the fuel line there was ample fuel still there, and did the blow check...no bypass. Also watching the jets I move the throttle and nothing, no fuel squirt at all.

So what do you guys think accelerator pump? I did not a bit of fuel residue on the cool carb® plate

[AKcharger]

wait wait...did google search everyone in the world has same problem, it's the accelerator pump

[AKcharger]

R2 accelerator pump and after 20 hours fires right up. I'll give it 48 hours next before I call it good

[AKcharger]

Gave it 72 hours..2 pumps on the gas peddel and fired right up so it was that little accelerator pump. Interestingly enough, it "LOOKED" fine, no rips or tears or other obvious defects

[LaOtto70Charger]

Good test.  My edelbrock does this all the time too. Need to check into this.

[jerry]

my 69 A-12 car has been like that for 30 years

[Kern Dog]

Gave it 72 hours..2 pumps on the gas peddel and fired right up so it was that little accelerator pump. Interestingly enough, it "LOOKED" fine, no rips or tears or other obvious defects

If I recall, the seal on the accelerator pump shrinks and loses it's seal in the bore that it travels in.

[Nacho-RT74]

If it was a TQ the first guess from me it was to be... cracked fuel bowl or cracked epoxy at fuel wells at bowl.

Really common failure

[AKcharger]

Well, problem back. Same thing, perhaps the accell pump went bad hat fast? I got an original Holley to on the '70, when I get it on I'll cross-cannibalize the eddy carb over to the '72

[Kern Dog]

Oh no...that sucks!
Ethanol gas evaporates faster than pure petroleum gasoline. All carburetors that I have seen have vents that are open to the inside of the air cleaner. This means that they can lose vapor and eventually the "fluid" of gas. The hotter the weather, the faster they will evaporate.
Also....Holley carburetors have the accelerator pumps at the bottom of the float bowl so even if the primary jets aren't swimming in fuel, the accelerator pump can still provide a pump shot. Carter and Edelbrock carbs need more fuel in the bowls before the accelerator pump will work as compared to a Holley. Sometimes with a Holley, you can get the engine to sputter long enough while cranking on just a few acc pump shots for the fuel pump to fill the bowl.

[c00nhunterjoe]

Oh no...that sucks!
Ethanol gas evaporates faster than pure petroleum gasoline. All carburetors that I have seen have vents that are open to the inside of the air cleaner. This means that they can lose vapor and eventually the "fluid" of gas. The hotter the weather, the faster they will evaporate.
Also....Holley carburetors have the accelerator pumps at the bottom of the float bowl so even if the primary jets aren't swimming in fuel, the accelerator pump can still provide a pump shot. Carter and Edelbrock carbs need more fuel in the bowls before the accelerator pump will work as compared to a Holley. Sometimes with a Holley, you can get the engine to sputter long enough while cranking on just a few acc pump shots for the fuel pump to fill the bowl.

  any carter/eddy setup i have had my hands on with a mechanical fuel pump will need some cranking to refill the carb after the fuel has evaporated after a few days of sitting. If this is happening overnight or in 1-2 days of sitting, then there may be other issues. But a week is normal in my opinion, especially as the temps increase.

[flyinlow]

I installed a Carter electric pump back near the gas tank . Only use it to refill the carb after a longer sit. Turn it on and it busses away for 5-10 seconds then quits when the carb is full. Turn it off , start the car with normal cranking. The engine driven pump with suck thru it. The electric pump will push thru the engine driven pump with the engine off.

It only puts out about 4psi , but it might get you home sometime if the engine driven pump fails, depending on whats wrong with it.

Holley carbs evaporate to empty also , it just takes longer.

The electricity in a Tesla will evaporate eventually if you don't keep toping it off.