Technical Vanishing Fuel

Rochester 2G 3x2 setup. 350 Chevy and a mechanical pump. After sitting a few days there appears to be no fuel in the bowls. Have to crank engine to refill them. Confirmed by looking down the carb throat and pumping accelerator. Otherwise runs pretty well.


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Welcome to modern reformulated gasoline that evaporates much more readily than the stuff that was sold prior to the adoption of fuel injection.

 

It's a way of life....get used to it....sorry

 

Kevin I have a 3-2 setup and it does the same thing...What I do is keep a can of starting fluid near by and spray some down the center carb, you may have to try this a few times before it runs...Miller

 

My tri power 57 Pontiac does the same thing.
I am going to put an electric primer pump on it to solve the problem.
Modern fuel sucks, just like 2020!
KK

 

an electric fuel pump is your friend....

 

Part time or full time?

 

I don't ever remember a carbureted engine starting like a modern fuel injected engine.

 

Yea, my fuel 'vanishes', too.
But the gremlins don't just take it when my truck is parked. It happens when I driving, too. If I try to outrun 'em, they just take more.

 

as a primer pump. cheapie free flow will do the trick. run it till it shuts off, start the car, shut it off.

 

An empty ketchup or mustard squeeze bottle works great.

Thoroughly clean any food residue, cut the tip a wee bit larger, and fill with gasoline.

If the vehicle has been left not started for a few days, remove the air cleaner, and fill the bowl of the center carb with gasoline through the bowl vent.

Now, if your carb is properly set-up, and you have a good engine, and good ignition:

Get in the car and set the brake.
Place the car in neutral
Roll down the window
Push the footfeed to the flow and release
Pump the footfeed once if ambient about 60 degrees F., three times if below.
Get out of the car
Reach through the window, and start the car. If ambient is above 0 F, should start on the 1st or 2nd revolution. If not, your engine needs tuning (or a different carburetor).

EDIT: the above will not necessarily work with a manual choke, and may not with an electric choke.

Jon.

 

Wow, I would never thought that it evaporates that fast! Makes a lot of sense though. I’ll stick with the mechanical pump. Just crank it a couple times then pump the accelerator. Thanks for the info fellas! Merry Christmas


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So does an empty Zippo lighter fluid bottle. Much sturdier plastic and easier to seal up when not in use.

Also. . . You don't have to clean out residual ketchup or mustard before you fill it with gas.

 

It's called 'gas' for a reason.

 

My Chevy 350 with a single Quadrajet does the same thing. More than about 4 days of sitting, and it takes a bunch of cranking to refill the carb.

 

How do you keep the fuel from evaporating from the ketchup bottle?


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Carbs with smaller fuel bowls with loose the new gasoline with 10-15% ethanol quicker. My WCFB's do not seem to have that problem in a week or two, I have 1/4" phenolic plates under each one. In one week I depress the foot feed to the floor to squirt fuel to the front and rear ports and it sets the choke on the rear one just up 1 step on the choke cam and it starts right up. If I wait 2 weeks I need to depress the foot feed twice. After 3 weeks or more I need to crank it 15 seconds. then depress the foot feed twice and it starts.
If I had a engine with 3-2's I would depress the foot feed to the floor on first start after a week. There should be enough residual liquid to squirt some into the manifold chamber to start; I would also make sure I don't touch the foot feed again only if it catches. Your center carb should have a choke. Good Luck

 

When I first read this thread title, I thought this was going to be yet another "Edelbrock AFB Carburetor" thread (and that includes the "Edelbrock AFB" on my truck that it REALLY happens with), but it happens with ALL carburetors (some just worse than others), and the current quality of gasoline we have. Best way to solve the issue, is like several have already said, "electric fuel pump". I am Butch/56sedandelivery.

 

I have the same issue on my 31, currently have a quadrajet, it also did the same with the previous Holley 4360 carb. Been thinking of adding an electric pump for initial start up.


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Close the cap. That's why today's vehicles have a closed fuel system.

 

My Pontiac is bad for it. I have a flow-through electric pump on a sprung pushbutton. Before going to crank, hit the button and wait for the pump to change note as it makes pressure against the closed float valve, then start the car as per the handbook!
Also useful in hot traffic when the pump begins to suck vapor, can push through some liquid fuel and prevent the car from stalling- another wonderful characteristic of modern fuel.

Phil

 

The solution I came up with is to drive 'em every day if at all possible. Don't give that crummy modern gas a chance to evaporate! Excuse me now, I have to take the '40 and the Nomad for their daily spin!

 

I only have about 500 miles on my 3 x 2G setup, but I haven’t had fuel go missing that I know of. Usually sits a week or two between starts. However, I have only used non-ethanol fuel thus far. That’s the secret. We can get it in some premium fuels in Oregon. Doesn’t smell as good as aviation fuel, but a lot cheaper.

 

Rochester Quadrajets have been known to have leaky well plugs that allow the carb to empty into the intake when the car is sitting (can also cause hard starting when it is warm from running ... basically floods the engine). I am not familiar with the 2G carbs but am wondering if this could be your problem. Both carbs come from the Rochester family so it might be worth looking into.

 

And I thought I was the only one..........

 

I and a number of Studebaker guys put on electric fuel pumps, which we usually only run for starting.

 

Mine vanishes too. Every time I leave a vehicle with gas in it, next time I get in it to go somewhere, it's almost empty. Never figured out how she can park my pickup in the same space I left it and make it look like it was never moved.....

 

Continual cranking to get fuel up isn't good on cam lobes and lifters either with today's shitty oils designed for roller cams and emissions.
Like mentioned, an inline type electric pump operated by a push button wired into the ignition circuit for safety.
https://www.aircraftspruce.com/categories/aircraft_parts/ap/menus/ep/fuelpumps_0facetelectric.html
I got one of these for my flathead - https://www.aircraftspruce.com/catalog/eppages/facetpumps.php

 

Where are you getting gas with methanol in it?

In California, it is 10% Ethanol.

 

Think I've found that maybe helps a little bit, though not particularly. The actual problem has something to do with what's called Reid index or vapor pressure or somesuch. When carburetors ruled the day gasoline had to have less volatile distillates particularly "summer" gasoline blends to prevent vapor lock. And that's what gasoline is after all, a blend of different refinery stuff. Maybe gasoline is still blended for summer and winter but I'm pretty sure they don't worry about anyone running carburetors. Carburetors are basically open to the atmosphere, fuel injection systems are not.