My return lines were leaking at the fittings, so I decided to take them apart and fix em.

Was looking at my buddies 94 7.3 and noticed his was much different, so I made mine look like his. Instead of a 3/8 line running from the IP to the rear of the block where it T's with a line from each bank then out to the tank and a line from the filter T'ed in between the fron 2 injectors.

Now it comes from the filter to the front of the first injector, no more T. Then IP to first injector on the other side. Back of the engine comes off both rear injectors to a T and out to the tank.

Anyone following me?

Anyway, fired it up seemed to run fine. Won't drive it till tomorrow. Is it going to work this way. Will it pose any problems? Seems much simpler this way with less fittings and connections to leak.

I have to admit, the injector return lines are still painted gray. Got to get that kit and get em changed. Truck is really running good now, way better than when I got it a couple weeks ago, no more smoke much more power.

 

If you disturbed the grey lines then yes there may be air leaks and hard starting in your future.

 

Yes, well aware of that issue.
Just making sure the rerouting this way isn't going to be a problem.
I am getting a kit and changing the caps and hoses. I haven't done it yet because it didn't run just right when I got the truck a few weeks ago so I was thinking of getting new injectors. Didn't want to throw on new caps and hoses just to do it again in a couple weeks. Now its running so good I think I will wait on the injectors, but not the return lines.

 

The return line routing you have should work just fine.
The biggest thing you need is the IP and the injectors are all tied into the return line somewhere.

The fuel filter return may be eliminated, there was a TSB about the check valve failing which can cause the filter to drain back to the tank while the engine is not running.
Many people have eliminated that line to prevent hard starting issues.

 

Thanks Dave.
Ran it around all day yesterday and no issues and no leaks, finally. Now I got to get that oil cooler leak fixed. No time off to get the seals. Guess I will check Napa or somewhere to see if they got any.

 

You may be able to get the gaskets at NAPA, but the O rings are either a Ford or International item.

 

Napa said they had something and it was $4. Can't remember what he called it but I knew it wasn't what I was looking for.

Going to have to take a long lunch next week to get them ordered.
Too busy at work, 60 hour weeks.

 

Did this apply to the N/A 7.3's as well?

I just noticed my filter return line leaking.

 

Yes the 7.3 and the 6.9 are the same engine except for the bore.

 

so the filter return line isnt a necessity? i can just eliminate it ? i only have hard starts in the morning because my glow plugs dont work. When its hot, starts right up.

 

Air in the fuel lines and bad glow plugs can both cause hard starts when the engine is cold.

 

Be sure not to run stater more than 20 seconds with 2 minute cool down as a starter might be the next purchase. $$$

 

Question to all;
Do I have my fuel supply setup correct ? the filter fuel return line is there to return excess fuel, which is under 5 to 9lbs lift pump pressure, to the tank, for the period the injector pump is not capable of accepting all the volume of fuel provided by the lift pump via the filter, plus the return line provides an outlet for air, that is always present in very small quanities in the fuel coming from the tank, to return to the tank again.
Why would I want to remove this line and force that small quanity of entrapped air to be sent into the injector pump ?
My truck runs a racor filter, electric pump, a standard mechanical pump in series, to a standard fuel filter, to provide the injector pump with 5 to 9 lbs pressurized air free fuel, plus this consistant pressure forces any entrapped air down the return line. The basic premise of my setup is that the return line should remain connected to allow excess fuel and air to return to the tank, and the addition of the electric pump always pressurises the line on ignition to provide immediate starts as the mechanical pump needs revolutions before it provides its best fuel delivery performance.

 

I would remove the stock pump from your system.

If the stock pump diaphram ruptures, the electric pump could fill the oil pan with diesel fuel.

The return line fron the filter has a check valve in the fitting at the filter header.
That fitting is getting hard to find.
If the check valve fails, it allows the filter fuel to drain back to the tank when the engine is not running, which causes the engine to run out of fuel and stop several seconds after starting.
To restart the engine you have to bleed the fuel system.

As long as you are not having a problem with running out of fuel several seconds after the engine starts, I would leave the return on the filter.
Since you have an electric pump, you will probably never have this problem.

 

Thanks for comments and here is what has occurred to this point.

1. some months ago developed the air in the line drama and all the issues that have to be dealt with from that drama.
2. decided to look for best options of a reliable fuel delivery
3. fitted new Raycor filter, new 4 to 6 lbs Carter electrical pump and a new standard filter and flapper valve and visually checked all lines
4. engine now started but required some time to reach a high cranking speed but then fired and ran well but at about 2800 rpm under load the fuel filter light would come on and at about 3000 revolutions the engine experienced starvation problems
5. so time to recheck everything and installed the following new parts from tank to injector pump pickup.
6. checked both tank pickups / tested tank switch / decided to fit a new straight arm mechanical pump and include it in the fuel delivery system with the electric pump / another new standard filter / another new flapper valve / new Schrader valve / fitted a fuel pressure gauge / egt gauge and again checked all to and from lines to tank.
7. installed new 4 kilowatt Mitsubishi starter
8. Thought that would resovle any problems and prepared to take risk with mechanical pump diaphram issue as pump was a new one
9. Combination of electric pump and mechanical now gives 5lbs at start and 9 lbs at 3300 rpm. No more starvation symptoms and engine revs to 3300 very strongly.
10. I have recently fitted a twin 3" exhaust and free flow mufflers and large cold air intake and now suspect I increased airflow but not fuel volume
11. I suspect the electric pump could not deliver adequate volume of fuel at the higher end of the rev range under full load conditions and the mechanical pump now makes up for that lack of volume, as it is activated by a cam that turns at a speed that matches the increase in revs of the engine
12. EGT varies between 600 to 700F depending on load and revs.
13. Engine starts immediatly I turn the key after glow plugs light goes out. No delay ever.
14. However I now wonder if the fuel pressure can be increased further for a even better injector pump performance.
15. I am waiting on delivery of a IP timing kit to start experimenting with the IP settings but that is another story that will develop.
16. Going back to the fuel filter return line issue. The fact that the line is a free flow unit, with the flapper only for stopping the air pull back at fuel cooling, do I lose significant fuel pressure through the return line ? that could be better utilized by the injector pump ? and everything I read makes me think that the fuel filter return line is important for allowing any air, that develops in the fuel from sloshing movement in the tank and any pumping cavitation effect during delivery to the injector pump, to escape rather than being sent to the injector pump.