OK, I read all the posts' in here and did a search througout the forum trying to find my answer. So now I'll have to post this ? I am taking out my 300 I6 "carbed" from '84 F150 and putting a 302 FI from an '88. I know what I have to do as far as the physical change over. But my ? lies in the fuel system. The '88 has tank pumps and a frame pump for fuel pressure. I've read the swaps from FI to Carb but not reverse. Will I have to put in fuel tanks and pump also or is there an alternative? Thanks.

And if any one is going to ask why, I own both trucks. The I6 is about shot, the '88 is going to get a Stroked 351W, so I have a spare engine.

 

you should be able to install pumps on the frame only just make sure you get the correct fuel presure i'm not sure how much but i know it is more than the carb fuel pump puts out you probley need a pressure regulator also

 

The regulator is going in with the 302, guess I have to buy another frame pump. Was just wondering if this would be adequate enough without the tank pumps also due to increased pressure requirements.

 

if you get a big enough pump you should be ok the holly projection kit does not require in tank pumps

 

This is all factory Ford FI system. My tech pubs in testing it should be between 40-60 psi.

 

Ford always put a boooster pump in the tanks, but aftermarket and swaps leave them out, including the one I did. Try and put the pump as low as possible for a siphoning effect. However, I tested a ford pump and it could suck gas 3 feet straight up.

Why not swap the tanks in too?

 

The '88 is going to need them for 351W Stroker going in.

 

My '84 only has a "F" port for tank switching and no provisions for fuel return like the FI motors. Was wondering if this would also cause some kind of problem not have a fuel return. If it is, I just might go ahead and carb the thing.

 

OK, have a question about the fuel returns. I work on aircraft and the FI engine system is equipped with fuel return. This goes into a small (1gal) header tank located behind the firewall. It is used as a collection point for fuel storeage for unusual attitudes to provide a constant supply of fuel to the high needs of the engine. If the fuel level was low enough in the wings and were banked high enough, it is possible for the lines to pick up air and starve the engine, which would immediately quit.
My truck has return lines only up to the tank switching port. From what I can determine, the unused fuel by the engine is returned to the tank at this point. Can anyone tell me why this system requires a return.

 

Research and answer your own ? Here's what I got from my data.


The pressure regulator and fuel pump work together to maintain the required constant pressure at the injector tips. The regulator consists of a spring-loaded diaphragm-operated valve in a metal housing.
The pressure regulator is located on the fuel supply manifold and installed on the return (downstream) side of the injectors. Downstream regulation minimizes fuel pressure pulsations caused by pressure drop across the injectors as the nozzles open. It also ensures positive fuel pressure at the injectors at all times and holds residual pressure in the lines when the engine is off.
The pressure regulator used in a multipoint injection system has an intake manifold connection on the regulator vacuum chamber. This allows fuel pressure to be modulated by a combination of spring pressure and manifold vacuum acting on the diaphragm.
Fuel in excess of that used by the engine, is bypassed through the regulator and returns to the fuel tank. The regulator shuts off the return line when the fuel pump is not running. This maintains pressure at the injectors for easy restarting and reduced vapor lock.


The question still stands. Is this necessary for the swap. Has anybody had a problem doing this swap without the return system intact.

 

doesn't the fuel pump use fuel for cooling itself
if it ran wide open and wasn't moving fuel through wouldn't it burn out.
The flow may not be constant enough to keep the pump cool without a return line. But then again it is emersed in fuel.
Maybe it has to do with keeping an even amount of pressure for the injectors
the excess pressure would have to be released some where.