I have a 1992 Ford F350 7.3 Turbo Diesel that all of a sudden is hard to start.Once it warms up it is fine.Last year thanks to many members of this forum I did some needed work to my truck that really made a differance, but the last two time I tried to start it I had a problem.First this is what I did to it;
New Glow Plug controller box from Ford(Seperate ground to battery)
New Glow Plugs from Ford
New Glow Plug harness complete from Ford
New Temp sensor switch from Ford
New O rings, retrun lines,clamps,caps on the injectors.I also ended replacing the fuel heater element and the line on the injector pump.Last weekend I got up early and it started right up.I drove it about 45 minutes on the parkway to take my little guy go-kart racing.It was fine.When I went to start it up to leave it spun alot longer than it usually does,stumbled a bit and started up.Puff of smoke out the back.It drove fine.I shut it off about 35 minutes later.We went in and out of 7-11.It fired up no problems.It sat for a week which is usually what it sits for being I drive it only on weekends.I went to start it this afternoon,same thing spun a bit stumbled and started up.Puff of smoke which I smelled but didi not see.I drove it for about 1/2 hour no problems. I restarted it a few times in the garage and it was fine.There is one location,passanger side last injector line where the return goes to the drivers side is a bit wet with fuel on the MANIFOLD ONLY and a bit wet on top of the rear manifold.Nothing on the line or near the cap,they were all dry. That return line goes under the turbo and rests about an inch under the turbo heat shield but there was no sign of a leaky line.The only other line I did not replace was the one in the back of the left side of the engine.The 3/8 one.I do not know where that one goes.It seems it goes down the back of the engine.Can it be air in the system ? leaking injector ? bad fuel ? The fuel sat for a few weeks in the rear tank.I add a bit of conditioner when I fill up and a few ounces of Marvel mystery oil. Any help would be appreciated.I am baffled but am leaning towards air in the system.
Thanks

 

Any external leakage means the system can drain down due to air intrusion. I would put an electric fuel pump between the fuel pump and the filter. Wire it to a switch in the cab. You can prime the system with it while the GPs are heating and while you crank, $45.00 on ebay or check with local auto parts store. At any rate your leak is the problem.

 

The turbo engines use a different return line routing than the NA engines do.

There should be no return line under the turbo.

Here is the return line routing I use, intake and top of engine removed.



Cross over on the front injectors.
Number 7 injector has a return tee with only one nipple that goes up to number 5 injector.

 

This morning I get in switch fuel tanks to one with a fresh batch of gas.It spun a bit but fired right up.I went to track with it.It sat most of day.I did tray and start it once.It fired right up.Im gonna let it sit a day then try again and get back to you guys.Thanks.

 

A couple things to remember.

The greater the distance is between the top of the engine and fuel level, the greater the pull trying to get air in the return system is.

A common question in here at times has been " When I park my truck with the engine uphill it starts much harder than it does when I park with the engine downhill, why is that?"

If you are running on the rear tank, with the engine up hill you have a much greater distance between the fuel level in the tank and the top of the engine.
If you were on the front tank, the distance is still greater, just not as much.

 

It was actually on the front tank when I had the problem.After the secon incident I went and got gas and filled the rear tank up which was almost empty.The first tank was 3/4.I ran it on the rear tank.I am gonn let it sit teo days or so and see wht happens.If it does it again im gonna go with air in the system .I just do'nt want to replace everything again.I will report back.
Thanks again