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Fuel Problem

Old Mar 20, 2008 | 10:37 PM
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78fordranger
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Fuel Problem

I have been having trouble with my fuel delivery. Its a 73 f250 4x4 390. I have a mechanical fuel pump that has 4psi on the inlet side and only putting out 1 psi if that on the out to the carb side. Does this mean the pump is still bad? even if it is sucking fine just not pushing it to the carburator.
 
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Old Mar 20, 2008 | 10:59 PM
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Not that I've ever checked the inlet side, but theoretically it should show very low or vacuum. Tell us a little more about the pump. Did you just replace it? Is it an existing one that has been working? It sounds like the somehow the lines are hooked up backwards or the check valves in the pump are installed backwards.
 
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Old Mar 20, 2008 | 11:27 PM
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On the inlet side you should show a vacuum. On the outlet you should show PSI. Without vacuum on the inlet side of the pump it can't draw gas from the tank. That is what gets the gas to the pump. I always installed an electric back up pump on the frame. I hated to be in the middle of nowhere and loose a pump & have to change one out. Where a backup electrical pump I could flip a switch & keep on going.
 
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Old Mar 21, 2008 | 07:13 PM
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No i am getting 4 psi of vacuum it has been working fine the last few weeks. It is a new pump on it then one day it wouldnt start. I got another post that explains it all but I dont remember where it is lol. my search isnt working.
 
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