I recently bought an ‘84 Ford F-250 from a guy who put a rebuilt carburetor on this truck and didn’t tune it. It runs great until it hits 45mph then it Boggs down and seems to want to die. How should I tune the carb to this?

 

Look for vacuum leaks. Look for a missing gasket.

Look and see if the A.I.R pump and it's components are missing

 

How much Vacuum should it pull on the gauge?

 

Not talking about the gauge talking leaks. Take a can of carb cleaner, and spray hoses, carb base, intake gaskets, etc. Listen for engine to raise from idle to higher rpm. You have found your leak.

 

Didn’t find a vacuum leak but tested my fuel pressure and it’s 1psi so I’m going to get a new fuel pump for it

 

Good find. I'm surprised it even starts

 

Every auto part store I have been to type in the make model and engine and it only shows mechanical fuel pumps that fit my truck. I am having a hard time finding where the fuel pump is located, I have followed the fuel lines clear back to the tank. Do they make electric fuel pumps that fit inside the tank like newer vehicles? Also I was thinking about putting an in-line external electric pump that pumps 6-8 PSI.

 

Fuel pump should be a mechanical pump, located on the left lower front of the engine, off the timing cover.

 

Replaced the fuel pump and it still Boggs down to the point of almost dying when I lightly accelerate and hit 45mph. It has new distributor cap and rotor, spark plugs, spark plug wires, fuel pump, rebuilt carb, ignition coil. Could it be the icm? Or maybe a diaphragm not working properly?

 

is it a single or double tank truck? I had a similar problem with my 86 f150 double tank. i could drive it, as long as i didnt get on the gas hard it would run ok. if i gave it enough gas to hold speed up a hill or try to get on the gas hard at all it would cut back and sputter. i went through quite a few part changes trying to fix it, distributer/button, plug wires, fuel filter. turns out it was the tank selector, super dirty foul gas in there, probably from the back tank that i never used. i took it totally out of the system. replaced with 2 straight fuel lines and its running great

 

Sorry getting back so late figured it out it was the vapor separator right before the carb. Couldn’t find a replacement so just ran a fuel pressure regulator in place.