holley 1945 losing its prime

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dirty white boy

dirty white boy

50 yr old Juvenal delinquent
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if i let my truck set more than couple weeks in summer, couple days in winter i have to fill my bowl with gas before she'll fire off!! ant no problem when its warm weather, lot worse when cold weather! try and spin engine in hopes fuel pump will fill carb but itll run battery down before that might happen! i dont get out every day or 2 but priming carb every time i go out last month or so is getting old! any ideas any body?
 
Probably not a carb or fuel pump issue but a fuel evaporation issue. Gas now days does that. There are many threads here about it. An electric prime pump is a solution. Electric primer pump for fuel
 
idk,..fuel stays a couple weeks in 100 degree weather, wont stay 3 days in 30 degree weather... dont think its a evaporation issue but ive been wrong before
 
dirty white boy said:
idk,..fuel stays a couple weeks in 100 degree weather, wont stay 3 days in 30 degree weather... dont think its a evaporation issue but ive been wrong before
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That's good to know. Clamp off the fuel line at the carb or disconnect and plug at both ends. Let it set a few days to see if the fuel is disappearing from the carb through evaporation (or leak). Somehow you need to separate the components to see where it's going.
 
Just had the same issue on my 71 Swinger, 1920 Carb....
It was the accelerator pump diaphragm, I put a kit in it, and problem went away!
Thanks
 
dirty white boy said:
if i let my truck set more than couple weeks in summer, couple days in winter i have to fill my bowl with gas before she'll fire off!! ant no problem when its warm weather, lot worse when cold weather! try and spin engine in hopes fuel pump will fill carb but itll run battery down before that might happen! i dont get out every day or 2 but priming carb every time i go out last month or so is getting old! any ideas any body?
Click to expand...
This is the main reason I went to an electric pump.
Engine fires off immediately now.

I blocked off crossovers, used insulator spacers, and even a full recirculating fuel system, but nothing solved the evaporation issue.
The electric pump did because of it’s ability to fill the bowls before cranking the engine.


Lift&Move said:
Just had the same issue on my 71 Swinger, 1920 Carb....
It was the accelerator pump diaphragm, I put a kit in it, and problem went away!
Thanks
Click to expand...

An accelerator pump can only solve that problem if there is sufficient fuel to pump.
That’s great that it solved your issue though.
 
In-line filter with a check valve before your carb won’t let fuel drain back

IMG_1950.jpeg
 
Slantsix64 said:
In-line filter with a check valve before your carb won’t let fuel drain back

View attachment 1716189702
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I've suggested those before......and always falls on deaf ears.

Regarding the evaporation. Usually, in cold weather, the humidity is low and evaporation rate is pretty high. When the weather is hot, humidity is usually a bit higher and that tends to lower evaporation rate. I'm no expert, though, since I've never experienced it.
 
I don't understand how the fuel can drain back out of the carb, when the fuel inlet is above the fuel level. On the holley 1920 carb if the pump diaphragm is bad the fuel can leak to the outside of the carb
 
Charrlie_S said:
I don't understand how the fuel can drain back out of the carb, when the fuel inlet is above the fuel level. On the holley 1920 carb if the pump diaphragm is bad the fuel can leak to the outside of the carb
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It just can’t empty the carb, no way no how.
It can only evaporate or leak.
It can however drain back what is in the fuel line.
If you have one that does both it compounds the problem.

My car has an electric pump so neither evap or drain back is a problem, but we have a 72 dart 318/two barrel that does both evap and drain back because it’s hardly ever driven.
That one is pretty much all stock, so it will stay the way it is for now.
A short shot of fuel in the carb and it fires right up.
 
Like Rusty, this usually falls on deaf ears .

www.forabodiesonly.com

"One-way" fuel line valve..?

Hi all My 198 slant starts very easily and fast when hot, but when it has been shut off for a couple of days, I have to crank several times to get it back to life. The time required for the mechanical pump to refill the fuel line and the carb bowl. I planned to install an electric fuel pump...
www.forabodiesonly.com www.forabodiesonly.com
 
Last edited:
TrailBeast said:
It just can’t empty the carb, no way no how.
It can only evaporate or leak.
It can however drain back what is in the fuel line.
If you have one that does both it compounds the problem.

My car has an electric pump so neither evap or drain back is a problem, but we have a 72 dart 318/two barrel that does both evap and drain back because it’s hardly ever driven.
That one is pretty much all stock, so it will stay the way it is for now.
A short shot of fuel in the carb and it fires right up.
Click to expand...
not a fan of electric fuel pumps and id only run one if it was set up to switch that tun off pump in event of a wreck!! and still only if going efi witch i just ant doing! if check valve dont help might be time to try out a 2 bbl carb!
 
dirty white boy said:
not a fan of electric fuel pumps and id only run one if it was set up to switch that tun off pump in event of a wreck!! and still only if going efi witch i just ant doing! if check valve dont help might be time to try out a 2 bbl carb!
Click to expand...

One would think the check valve should help at least.
 
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