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Old 05-10-2011, 11:46 PM
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Motorcraft 4300 carb

Has anyone had any problems with this carb flooding and the needle and seat will not shut the fuel off. I'm currently working on a completly restored 1974 AMX and this carb was working fine till it sat for a couple of months then it kept flooding when trying to start. I fiqured that the needle was stuck, etc. but upon inspection the parts where new and no sign of wear. I replaced the needle and seat with a new one and adjusted the float per spec etc.the problem is still there. The system is running a stock mechanical fuel pump with aprrox 7 1/2 - 8 lbs of pressure. Any ideas anyone ?

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Old 05-14-2011, 10:03 AM
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7 1/2 -8 lbs is a lot of pressure for for your carb. Range would be better at 4 1/2 - 6 at the most. Might try an in line fuel pressure regulator just before the carb. That should do the trick. Whats happening is the pressure is over coming the ability of the small float in the motor craft to keep the needle valve on the seat
What engine do you have in the AMX? I had a 68 AMX and a 71 javelin back in the 70's. The first thing I did to both engines was toss the motor craft carb for a Holley square bore 650 cfm. The performance was a lot better over the motor craft.
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