Carb Fuel Evaporation?

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wheelsport

wheelsport

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Many of our old cars have the problem hard starting after sitting for long periods. My car is no exception. This subject has been discussed a number of times. The fuel disappears out of the fuel bowl for whatever reason. Some of the people on this forum have installed backup electric fuel pumps. I plan to do this but I found a problem with some of the pumps on the market. They don't all allow fuel flow when not turned on. I want a electric pump I can fill the carb and then run on the factory pump. What pumps have some of you guys used?
 
How long between last startup are you talking about?

What ambient temp are you talking about.

Can you get alcohol free gas in your area?

How many seconds of cranking is too much?
 
Some times after only a week I need to crank for almost 30 seconds or more. My garage is usually around 45 to 50 degrees in the winter. I have this problem even in the summer. There are several real gas locations in my area. As far as I know the starter in my car is original and I don't want to over work it. The car has 10003 original miles.
 
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wheelsport said:
. The car has 10003 original miles
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Is that all!
150,000 plus on the last rebuild (321,000 on my 67 dart). I would have to look to see if starter has been replaced.

Have you verified that your carb is empty BEFORE you attempt to start it?

I live on Northern Colorado. Garage gets between 25 and 85. If I drive the car, 2 to 3 days later, 2 pumps, crank 1 pump, crank, start,

If it sits a week or more like today sat for 10 days, 2 to 3 pumps, crank 1 pump, crank, 1 pump crank, start.

273 2bbl stock.

I have verified that there is fuel before cranking and even after 2 weeks there is still fuel in the bowel enough to give 5 to 6 good squirts.

My typical cranking time is 3 to 4 seconds at a time. I would not crank it for a continuous 30 seconds.
 
My air filter barely fits under the hood now. There's no room for a spacer. I have verified that the carb is empty after less than a week.
 
I live across the river from you and yes this is an issue with the fuel we get here in the NW. Today fuel is design for EFI and Emissions and formulations change from winter to summer. My F-150 I had to crank quite a bit to get it to start after sitting months at a time outside. My Dart, not so much, it lives in the Garage but the Holley I have on it will slowly evaporate the bowls dry from sitting with a spacer, bowl shields and heat barrier coatings on the carb. I have an Edelbrock mechanical pump only and honestly, it moves fuel pretty well and even after a month of sitting only a few turns and I have fuel to fire. I have a Dakota starter which I think turns the motor over faster too, that helps the pump.

If going electric, look for one like this where it states "This model does not have a one-way check valve or an anti-siphon valve, so fuel can be pulled in either direction when the pump is turned off"

Mighty Mite 12-426 25 GPH Holley Mighty Mite Electric Fuel Pump, 1.5-4 PSI
 
Actually if you are using an electric pump, I would NOT plan on "not running" it at times. Either run an electric through a mechanical and always run it powered or get rid of the mechanical pump

Part of the problems with modern fuel is that it boils more easily.

Boiling point is partially determined by PRESSURE, and when using "only" a mechanical pump it is bad enough.........the pump being up front causes a low pressure in the tank to pump line just because of physics, and this alone somewhat lowers the fuel boiling point.

Now, if you come along and add an UNpowered pump, you add more restriction.......which causes the mech. pump to further lower line pressure, and further lowers boiling point

My car is STILL torn apart. But before I went to EFI, the smartest things I did was --convert to electric pump, -- build a fuel return system using an orifice equipped Wix filter,---and use a carb thick insulator spacer.

"It might be" that Edelbrock carbs are somewhat worse for fuel boiling/ evap because the bowls are right down on the manifold, effectively.
 
I use a Facet style pump (the cube) to prime the system. Mounted next to fuel tank.

It just acts like a check valve when off with virtually no resistance to flow.
 
I crank a few turns and pump the **** out of it. Crank again just a few turns and repeat until it starts. If I sit there and crank constant I can kill my Battery. As said it's a common issue. If you say come out of a store on a hot day and have this issue you need the Phenolic spacer . You should have the spacer anyway.
 
Have you verified the fuel evaporation? Have you removed the air cleaner and looked into the carburetor throat and operated the accelerator pump to verify fuel shot or lack thereof?
 
If its that big of a deal to you then keep a squirt bottle with gas in the garage and manually fill the carbs fuel bowl through the vent.
Voila instant fuel.
 
Kendog 170 said:
I crank a few turns and pump the **** out of it.
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You might be flooding it?
Right from 67 owners manual...
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1642608037226431046183847120610.jpg
16426080546397601751480779065726.jpg
 
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Dana67Dart said:
You might be flooding it?
Right from 67 owners manual...
Click to expand...

I'm not. There is no gas to flood with hence that's why I'm pumping. My ride gets two pumps and choke and starts right up. but if it sits a Month that's how I start mine. Doing it since 1985 even after a rebuild.
 
I found with the choke fully closed you can get gas back faster. Remind you I'm talking after sitting a long period .
 
Kendog 170 said:
I'm not. There is no gas to flood with hence that's why I'm pumping. My ride gets two pumps and choke and starts right up. but if it sits a Month that's how I start mine. Doing it since 1985 even after a rebuild.
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What carb are you running?
 
I ran a stock 68 AVS on my 340 in my 65 and that thing would not hold gas for more than about a day. Not sure what was up but I put in a carter electric pump and every morning Id turn the pump on manually with a switch under the dash and it would pump for about 5 seconds ans then slow down to almost nothing. Motor would start instantly every time. If I didnt run the pump, the car would start (maybe) but would be very lean and would die after about 10 seconds. Forgot a few times and started to sputter on the street until I flipped the switch and off I went. Good theft deterent too. The Facet jigglers are just one way check valves on a little magnetic shuttle going back and forth. The way they are designed is they allow fuel to flow through them but not back. The forward motion of the shuttle would compress the fuel in the line to the carb and on the way back will pick up more fuel. They were self regulating 1.5-3 psi if there was enough pressure in the carb side, the electromagnet force would not be strong enough to cycle it forward and it would just sort of vibrate.
 
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68 /340 1st stock 600 carb, then eddy 650 carb. then stock 440 750 carb. All started the same.
 
Is this another hit and run?
 
Kendog 170 said:
68 /340 1st stock 600 carb, then eddy 650 carb. then stock 440 750 carb. All started the same.
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All AFB style carbs. I like those carbs but they are prone to fuel evaporation.
 
I found the Eddy and Carter style carbs have the evaporation problem. I prime my hemi with a bottle I'm not going to crank long enough to fill two carbs, tried it.
 
Sometimes I don't drive my Dart for a month, when I go out to start it, I let it turn over for 8 seconds without touching the gas pedal, let it set for a couple of seconds and do it again, then I pump it 2 or 3 times and it starts right up, I have to mess with the gas pedal to keep it running. I have a 340 with a Edelbrock 800 AVS2 and their insulator gasket. No choke.
 
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