I know others have had this issue, where after the car sits for a week or more, it takes a lot of cranking and pumping to get the gas to the carb.
If I prime the bowls, the engine cranks and idles with a short twist of the key.
I think the gas in the carb is evaporating, especially after a long drive when hot. Some have also said that gas seeps back to the tank after a while. I don’t know if a check valve, or an electric pump, or both is the answer. I’m also hearing conflicting answers about leaving the mechanical pump in the mix after installing an electric one.
For those who have had and/or solved the issue, what are your thoughts?
Hi, what carburator do you have and is it the mechanical fuel pump?
My 4300 4V is bad about emptying the fuel bowl after driving on a hot day. The heat percolates the gas out of the carb and floods the engine. Requires a fully open throttle to restart.
Otherwise, it will start right up after sitting for a week, but not after a month or more when the fuel has time to evaporate from the bowl
I believe this is simply a matter of fuel evaporating from carbs.
I experienced this with both of my recent carb powered cars, even when using ethanol free fuel. For both cars, I’ve had a slight fuel smell in the garage indicating some level of evaporation through the vent and a bit from fuel weeping through a gasket. When I recently pulled the carb off for a rebuild build, the fuel smell was pretty much eliminated.
There only seems to be a few options in dealing with the fuel evaporation:
- Live with it and let it crank to refill the bowls
- Manually fill the bowl when letting it sit - I bought a small chemical bottle with curved tip
- Install an inline electric fuel pump to pre-prime engine before cranking - I have a few friends that have done this on their carb cars, but eventually switched to EFI
- Install an EFI setup
Just my quick $.02.
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Autolite and motocraft carbs had issues with leaking power valves. Back in the day it was not uncommon for new valves to leak right out of the box. Especially if one had a tendency to over tighten them. The fuel pump check valves and the needle and seat should prevent fuel from running backwards from the carb. Fuel evaporation could be an issue and can be compensated for by adding thicker carburator to manifold gaskets. However a leaky power valve will drain the bowl every time. Just my thoughts fwiw.
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It’s a stock Fomoco 2000 or 2100 2v on the stock mechanical fuel pump.
Yeah, I think you got it. I also use a small squeeze bottle to fill the bowls. It may be best to just deal with it. LOL
It’s often better to leave one small problem alone so it doesn’t become two.
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