i have a 1985 f350 crewcab with a 6.9liter can anybody explain to me how the return lines are supposed to be routed or is there a diagram to show the correct routing. the previos owner really messed with every thing on this truck, but with a little patience ill have it back to normal. thanks to anybody that can help.

 

There is a return line that comes off the filter header to injector #1 (front passenger side of the engine) that should be eliminated. From there the return lines run injector to injector to the back of the engine. At the last injector it crosses the back of the engine to a block located before but near the #8 injector. At that block it tee's with two other lines, one goes to the rear of the truck, the other goes to the #8 injector. From the #8 injector it runs injector to injector up to the #2 injector. A line from the top of the IP also ties into the #2 tee.

I may be able to take a picture tomorrow, I am in the process of taking mine apart.

 

that would be great because mine is nothing like that. mine is middle ways of passenger side fuel rail there is a line, same on other side these two lines come together and join into one line that hooks up on the little nipple on the fuel line going to the ip. do you think this is my hard start probblem?

 

that could be the hard start problem, but i doubt it. beneath the plastic caps are fuel proof o rings that act as seals to the return caps. these o rings become dried out, from the low sulphur fuel, and allow air to be drawn into the return line system. There are repair kits available (injection shops) to replace the o rings, caps and fuel line in the return system. That is probably the first starting point. The return system runs from the front of the engine to the rear where the lines meet and return the fuel to the tank, as mentioned by Dave. If you have to crank to get it started, DONT CRANK ON THE STARTER too long at one time, they are a weak point in the system and become overheated.

 

as dave had mentioned do i have to disconnect the line from the filter housing to the no1 injector? and he said there was a line that came from the ip to the no2 injector, mine doesnt have this line and is it supposed to, and if so where does it hook up on the ip?
thanks for any help

 

The return line hooks up to the brass fitting on the very top of the IP.
The return line to the tank is at the rear of the drivers side head, should be bolted to the rear of the intake manifold.

The important thing is that each injector and the IP are hooked to the return line. Routing is not critical.
Since I have a turbo, my return line strarts at the rear of the passenger side head and runs to the front. The crossover line goes 2" toward the IP and has another tee there that the fuel filter line hooks to. Then it continues under the IP to the front of the drivers side head. The line then runs to the back of the drivers side head and comes off to the return block. The return from the IP, the line from the drivers side head and the line to the tank all hook together there.

When you install a turbo you basically just turn the return line setup around on the engine so the return line is not under the turbo.

The reason I said to disconnect the filter return line is that is a common place for fuel to bleed off and cause hard starting problems. Ford issued a TSB back in 89 or 90 about hard starting after sitting overnight. The fix was to eliminate that line.