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After my truck stays parked for a few days the gas in the fuel pump glass bowl is gone.
I order a new fuel pump thinking the check valve in the pump is bad.
Would you'll agree? Thanks

Probably not, modern gas evaporates much quicker then it used to. Most everybody on this site has to crank the engines for a short time to refill the carburetors.

LeLou,

Down here in south La. with the heat we've been having the gas is just evaporating. If I don't start my truck every couple of days I will have to crank it a bit because the carb will be empty.

Tommy your right about the heat in south louisiana, but do you think the fuel in the fuel pump will evaporate to?

Lelou , we might be able to give you some suggestions if you would tell us what your working on. It's always best to lead off your posts with a short description of what truck your working with, i.e.; 1955 1st series w/235 and Rochester carb losing fuel when it sets for awhile. Help us help you.👍🏻

It's a big problem here in Hawaii too. Is there a check valve I could install in the gas line closer to the carb to minimize the cranking time to refill it?

LeLou,

Maybe there is a check valve in the pump, I don't know. I don't have a pump with the glass bowl, just my experience that a few days without running the truck and the carb. is dry.

Every machine I have that sits awhile has an electric priming pump on it; fork lift, compressor, and old cars/trucks. Flip electric pump on till it changes sound then hit starter and they fire instantly. Once started electric pump is turned off as the mechanical pump will draw through it just fine.

How long do you have to crank the starter for the pump to fill the carb and start?

52Carl In my opinion to long. I'm worried about a 6volt starter on a 12volt battery overheating.
What i'm trying now is shutting off the valve at the gas tank and monitoring the gas lost in the
fuel pump bowl. That would tell me if the check valve in fuel pump is leaking

2 seconds
5 seconds
10 seconds
20 seconds
?

Fuel evaporating out of the carb is normal, they all do it. Once the carb is dry, the float opens the needle and seat. The fuel now evaporates out of the line and filter by way of the seat opening. It continues down the line to the pumps, where the check valve should seal off the main fuel line.

Adding a 1/4 turn shut off at the carburetor inlet will minimize cranking, but then you need to be under the hood overtime you go to start it.
Electric primmer pump is the quickest and easiest fix.

I just Googled 'fuel line check valve' and came up with several different options, some under $10. If a check valve was mounted up by the carb it should eliminate the evaporation of fuel in the line from the pump. Any reason not to install one of these?

Do not worry about the 6 volt starter fed by 12 volts. If the starter isn't cranking the engine over smoothly and rapidly, check/clean all cable connections, or have the starter rebuilt or find another one. They go bad regardless of whether they are fed by 6 or 12 volts.
Install your new fuel pump to see if it solves your problem.
A good 6 volt starter fed by 12 volts with a good fuel pump, with clean/open/leak-free fuel lines should fill the carburetor bowl in less than 10 seconds.
Carl

Thanks Carl, I agree, fuel pump coming in. I'll let you know how comes out. Right now i'm cranking over or
close to a minute.

Just went out and started up my '55. Its been sitting in Calif heat for 2 weeks due to my back surgery. Cranked over with ignition off until steady pressure on pressure guage. Then turned on ignition, 3 pumps of accelerator pump, and it fired right up.