Hi all, I am new to this forum and I am building a 1967 mustang 289 with a Holley 4150 600 CFM carburetor with a vacuum secondary, and an electronic fuel pump.
Recently my brother and I started the car for the first time and we have been uncovering problems (mostly minor) ever since. We have been trying to figure out why we are flooding the engine now when just a few days ago the problem didn't exist. The car will start quickly and run with a very rough idle for about 2 minutes then sputter and die. When it dies I have been pulling the spark plugs which are soaked in gasoline (no oil) and drying them, reinstalling, and troubleshooting. While running we are getting a lot of movement in both the tachometer (500-1500 RPM) and vacuum gauge (5-8), but that is nothing new.
We have tried the following: I have read online that one common problem is a bad power valve which I have since replaced with no results. I have tried all types of adjustments to the mixture and idle screws with no change. We have looked and looked and looked for vacuum leaks and can not find a single one, and currently we have every vacuum port on the carb closed with the exception on the timing advance and the PCV which is connected to our vacuum test gauge. We have checked and rechecked the floats in the fuel bowls and all appears to be fine.
I am thinking that we may have too much fuel pressure coming from the electronic pump. Does this sound logical? I do not have a fuel pressure regulator in the line nor have I connected a pressure gauge to see where it is. To my knowledge Holleys don't work well over 7.5 PSI and my fuel pump ranges from 4.5 to 9 PSI per the manufacturer.
Please give me any suggestions you may have as to what to look for/test. Any recommendations will be very much appreciated.
Recently my brother and I started the car for the first time and we have been uncovering problems (mostly minor) ever since. We have been trying to figure out why we are flooding the engine now when just a few days ago the problem didn't exist. The car will start quickly and run with a very rough idle for about 2 minutes then sputter and die. When it dies I have been pulling the spark plugs which are soaked in gasoline (no oil) and drying them, reinstalling, and troubleshooting. While running we are getting a lot of movement in both the tachometer (500-1500 RPM) and vacuum gauge (5-8), but that is nothing new.
We have tried the following: I have read online that one common problem is a bad power valve which I have since replaced with no results. I have tried all types of adjustments to the mixture and idle screws with no change. We have looked and looked and looked for vacuum leaks and can not find a single one, and currently we have every vacuum port on the carb closed with the exception on the timing advance and the PCV which is connected to our vacuum test gauge. We have checked and rechecked the floats in the fuel bowls and all appears to be fine.
I am thinking that we may have too much fuel pressure coming from the electronic pump. Does this sound logical? I do not have a fuel pressure regulator in the line nor have I connected a pressure gauge to see where it is. To my knowledge Holleys don't work well over 7.5 PSI and my fuel pump ranges from 4.5 to 9 PSI per the manufacturer.
Please give me any suggestions you may have as to what to look for/test. Any recommendations will be very much appreciated.
