94 carb leak down
 

Why do the carbs loose their prime, must be a regular thing with lots of guys using electric pumps to prime the carb after sitting a few days ect ? I've got one that does it, runs good new power valve (flat base good seal), can't smell gas in oil. Don't want to put prime pump on it because i shouldn't have to. No leaks everything tight.

thanks kurt

Re: 94 carb leak down
 

Couple of things...
1) these carbs are open to the atmosphere. Evaporation at work.
2) Fuel pump is not working properly. There is a check valve within the pump that prevents fuel from flowing "backwards".

I tend to pull the choke out when I shut a car down during summer driving months. that does slow down the evaporation.
My '36, during winter storage, is started once per month. I simply make certain the choke s pulled out, pump the throttle a few times and hit the starter button. Within ten seconds tops, the engine fires.
Both the fuel pump and carb were rebuilt by Charlie Schwendler.

Re: 94 carb leak down
 

I have always had the same problem with all collector cars that don’t get driven often. Fuel in the carburetor bowl evaporates. I think it is just less of a noticeable problem with cars from the fifties or newer. The 12 volt engines crank faster, fuel pumps pump faster. Henry’s fuel pumps were “just good enough”, so takes some cranking to fill the carb.

Re: 94 carb leak down
 

That’s a good idea on pulling the choke to limit evaporation. Thx!

JB

Re: 94 carb leak down
 

I run an electric fuel pump in line. When the car sits I let it pump up. Once it slows diwn I start the car and shut the electric pump off. The car can be sitting fir two months and she will start the first or second attempt ….

Re: 94 carb leak down
 

I found my mechanical fuel pump was a lot of what I though was my carburetor leak down problem. The top and bottom were warped enough that fuel was evaporating through the diaphragm. I lapped the fuel pump split line flat while rebuilding the fuel pump and now the car can sit twice as long before long cranking sessions on the starter are required.