HI all wondering if anyone out there may be able to help me with my 1985 f350 460 4180 holly carb. The problem is that it wont hold speed at highway speeds. I first thougth it was when the 2ndarys opened up. But now i do not think that has anything to do with it. It seems to be a sweet spot in the throttle just befor the 2ndarys open up that on flat ground will let it cruise about 60 but attempting to give it more throttle to climb a hill or pass it looses power. At times it will backfire when this happens. I thought maybe a power valve replaced the power valve and installed the new power valve saver by holly. I felt pretty sure this was the fix but same symptoms. checked the egr today it seems fine. Any thoughts are appreciated.

 

May be the fuel pump or dirty fuel filter not giving it enuf gas.

 

....or float bowl levels too low. In addition to the small brass filter in the carb inlet, the 3 way/fuel return device also has a filter inside and it could also be causing a fuel delivery problem.

 

Thanks I looked at the filter in the carb but did not know about the one in the the 3 way vale. No wonder it is so big I will check it in the am thanks again.

 

Hi all wanted to let you all know what I found on this. apparently ford used 2 types of fuel pumps on these. Mechanical and electric in the tank and if it has duel tanks electric and mechanical with the electric pump in the rear tank only. Mine is electric fuel pump only. the electric fuel pump uses a diffrent type filter on the carb. Mine was the stone type filter. Im not the origonal owner so im not sure rather some one changed it or ford screwed up. The one that belongs on it is a fiber type filter. I assume what was happening is that the presure from the electric pump was pushing the stone against the fuel intake and restricting it. Changing to the right filter and reseting the bowl jets appears to have fixed the problem.