The Ford Barn

robib · 03-23-2025, 05:50 PM

To start off, the fuel we use today is not like that of "yesterday's gasoline". The boiling point of today's fuel is much lower, which can lead to many problems with carbureted engines. The problem I hear most often is hard starting with a hot engine after the car has been sitting for a short time. This is the first problem you asked about.

Your car has tripower, which means you have a fuel rail along with the three carbs. When you shut the engine off, the temperature of the engine increases (can go over 200 degrees F) from the lack of coolant flowing. The temperature of the fuel in the fuel rail and the carbs also increases to the point that it starts to boil. The fuel also expands and has no place to go except to override the needles and seats in the carbs. So now the fuel dumps into the intake manifold effectively flooding the engine and a very hard "HOT" start. With a single carbureted engine a fuel pressure regulator could be installed right at the carburetor, which would stop any additional fuel from entering. There still would be fuel in the carburetor which could expand and enter the intake, but the effect would not be as bad. With tripower, you would need three regulators and there location would "where"? I have one other thought. The other brand (GM), has fuel pumps with return lines to the fuel tank as a stock system (70s cars). If you could set up a return line (1/4"), that may stop your hard starting problem. As stated above, we are not dealing with gasoline, we are dealing with fuel designed for today's fuel injected engines. I hope this has given you info and ideas of how to "fi" your problem.

03-23-2025, 05:50 PM	#2
robib Member Join Date: Mar 2013 Location: Canton, Ct Posts: 37	Re: Tri-power issues To start off, the fuel we use today is not like that of "yesterday's gasoline". The boiling point of today's fuel is much lower, which can lead to many problems with carbureted engines. The problem I hear most often is hard starting with a hot engine after the car has been sitting for a short time. This is the first problem you asked about. Your car has tripower, which means you have a fuel rail along with the three carbs. When you shut the engine off, the temperature of the engine increases (can go over 200 degrees F) from the lack of coolant flowing. The temperature of the fuel in the fuel rail and the carbs also increases to the point that it starts to boil. The fuel also expands and has no place to go except to override the needles and seats in the carbs. So now the fuel dumps into the intake manifold effectively flooding the engine and a very hard "HOT" start. With a single carbureted engine a fuel pressure regulator could be installed right at the carburetor, which would stop any additional fuel from entering. There still would be fuel in the carburetor which could expand and enter the intake, but the effect would not be as bad. With tripower, you would need three regulators and there location would "where"? I have one other thought. The other brand (GM), has fuel pumps with return lines to the fuel tank as a stock system (70s cars). If you could set up a return line (1/4"), that may stop your hard starting problem. As stated above, we are not dealing with gasoline, we are dealing with fuel designed for today's fuel injected engines. I hope this has given you info and ideas of how to "fi" your problem.