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Discussion Starter · #1 ·
I just installed my 87 rebuilt 460 in my F350 4sp. I went with a Biggs 750 carb that the guys tested and set up before shipping to me, and D.U.I (Davis Unified Ignition) distrubitor and their one wire Ford alternator. The engine starts right up, but runs at high RPM for aprox 5 -8 seconds and sounds great, but then dies. As my F350 has duel fuel tanks, I Have two "T" fittings in my custom 3/8" steel fuel line feeding the carb. One handles the fuel coming in from the front and rear tank, exiting to the second "T" which feeds the carb inlets. I Have good compression, oil pressure, and I assume good vacuum, and it appears enough fuel flow as the accularator pump in the carb does spray fuel when pumped by hand. The truck has a low pressure fuel pump in each tank, with a high pressure pump mounted to the frame, with a tank selector valve. I get the same symptoms from either tank. I did eliminate the Ford "T" where the two tanks converged, which suspect had a check or regulator in it, but did close of one tank line to eliminate back feeding but there was no change. It still seems like a fuel starvation problem to me, but the very high starting RPM leads me to think excessive vacuum? or timing advance ( vacuum line is disconnected and plugged) or perhaps the ignition ss cutting out after a few seconds for some reason. Does anyone have any ideas on how I can further troubleshoot this problem?
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DAustin
 

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This is a wild guess, I will just throw this out, you may have an intake gasket or bolt leaking air when it first fires it runs but is loosing vacuum after the first fer seconds of running making the mixture too lean to burn????? What do you think of this idea??? Just shooting in the dark.
Bill Bailey
 

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Discussion Starter · #3 ·
Vacuum leak is a good diagnosis. I pulled the intake to reseal it and should have new gaskets tomorrow.
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Discussion Starter · #4 ·
I am up and running! I had put a manual oil pressure gauge in the port where there was an electric "switch" on the tee in back of the engine, along side the oil pressure switch (just for initial start) turns out this "switch" keeps the electric fuel pumps energized as long as it closes after a few seconds- via oil pressure!
 
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