If my 38 sits for two days it won't start. Gas down the Carb a couple of times gets her going. Runs great after that and starts fine unless it sits two days. Has a rebuilt fuel pump but I am guessing it's the problem. I have a vaccume guage but not sure how to use it on a pump. Hate to change out the pump if it's OK and maybe a problem with the Carb or fuel lines. No visable lakes in system.

I'm guessing here but it sounds like you may have a piece of crud holding one of the valves in your fuel pump open, allowing the fuel to siphon back out of the line. If you have a glass bowl pump check for fuel level in the bowl prior to start up. If it's empty that's likely the cause. I have the same issue but it takes a couple of weeks for mine. Another thing that doesn't help is the W1 bowl isn't air tight (mine isn't anyway) so the gas in the bowl can evaporate pretty quickly.

Do you think the glass bowl should stay full all the time?

I'm on my third carb. All of the carbs lose the fuel after sitting a few days. After cranking for 6-9 seconds it finally starts the starts instantly after warmed up.

1..Rochester
2 ..Carters

[quote=Joneses]Do you think the glass bowl should stay full all the time? [/quote

How is your gas tank???....The glass bowl on top of your fuel pump (if you have one) should normally be about 1/2 full.
When it won't start you should remove the glass bowl and check if the small round brass filter screen on top of the fuel pump (under the glass bowl) is not clogged up with fine,sand like,debris from your gas tank and fuel lines.
Before I changed out my gas tank I used to carry a small stiff brush with me and when the car would not start I would remove the glass bowl and brush off the fine screen filter,and go on my way....Good Luck....ED

All carbs are vented to air or a charcoal canister of some type, remember they are not like the newer cars. All of my older cars have have to be cranked a little more when they have set for awhile.

That's what the choke is for. Use it.

You're welcome,
Charlie

The fuel will evaporate out of the carb bowl. I installed an electric fuel pump to save wear and tear on the battery. I only use it to prime the carb and then shut It off. With this method, It starts right up every time no matter how long it sits.
Richard

New info: New fuel tank and lines. No amount of cranking or choke will work. If I have to replace pump would like to test it and the new one to make sure what is going on.
Merry Christmas

Have you disconnected the fuel line at the carb. to see If the pump is working? I assume It Is if It runs after priming the carb. A vacuum only gauge will not help you determine proper pump pressure. You would need a pressure gauge for that.Many gauges have both a vac. and pressure function.
Richard

I think my guage has both. Don't have any instructions on pressure, vaccume or how long it should hold before leaking off.

3 to 3 1/2 lbs. will indicate a good fuel pump.
Richard

About half-full is normal...You didn't mention the type of carburetor...I had a Rochester awhile back that acted like yours...Turned out to be the fuel/plunger accelerator thingy on the carb had dried out...You probably don't have a Rochester, though. I had to prime it when it had been sitting because of that...

Thanks all for your comments, will let you know what I find.

Sounds like the accelerator pump in the carb but I would look at the hose that connects the fuel pump to the fuel line as they are known to collapse on the inside.