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I have a 1984 chevy 454 with a carb, a inline electric fuel pump. I can see the fuel flow into the carb. I lso changed out the carb fuel filter as well as the fuel tank filter. every time i start the enigine, if it starts runs for a while and then putters out. what could this be?
I have had some people tell me the engine runs with a rich fuel mixture. but if that is the case why does it sputter and die? Did I mention I changed out the carb fuel filter.
The carborated engine in your unit may have one of several failures. 1st the choke. If the choke does not come off it will cause the engine to quit and produce black smoke eventually. determining why this is not working correct depends on whether it is a 12 v heated choke coil or not. If it is check for 12 volt power and ground at the choke coil. 2nd the needle valve in the carb could be leaking. It will cause flooding and stalling. With the fuel pump running the fuel will trickle through the ports in the throttle bores at the throttle plate level causing rich mixture flooding and stalling. Need to check fuel pressure to insure it does not exceed the max spec for your carb. 3rd the carb may have leaky welsh plugs in the bottom. They will leak into the vacume area of the carb base and cause your symptoms as above. To check the carb has to be torn down and the bowel filled to see the fuel leak by. Very rare for this to leak enough to cause your symptoms but I have seen it. 4th I have seen a poor running black smoking unit that stalls have a burnt or bent intake valve. This causes the other cylinders to run poorly and rich.
Start with the top and work down. My list will cover 75% of the carb problems that cause this. Good Luck
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