Ford 3000 diesel - Return line question

Found the leak on mine, it wasn't at the injector itself but the return hose between injector 1 and 2 has a small hole it is weeping out of. I believe who ever did this and cut a lot of the hardlines and replaced with hose did not use a fuel hose for diesels as it is brown and oil soaked and needs to be replaced.

So my question is two fold, first question is what size is this return hose for a '68 (if my research is correct) Ford 3000 Diesel? My second question is what hose should I look for that will work with diesel fuel and not result in this issue coming up again.

When I did my 68, I THINK it was 3/16.

I got the hose from Napa, they sell it by the foot. It's not heater
hose, nor vac line, and not their basic gas line either. It is a line
rated for diesel, but not immersion. Ie, its interior surface is
more diesel resistant. When you cut it you will notice a black
latter sheath and a grey inner core.

So it should be fine to use to replace the fuel tank to lift pump hose as well as the lift pump to filter hose as well with this?

The previous owner or owners cut a lot of the hard lines as I believe the tank to the lift pump and the lift pump to the filters were all hardline. Cant find replacements and the photos I see shows the tank feeding the lift pump from the top and the bottom is going to the filter where mine is feeding from the bottom of the lift pump and going from the top to the filters.

I went ahead and did my oil change as well as the oil in my injection pump, what came out I didn't know what it was, it looked like oil but it smelled like atf maybe kerosene. I went ahead and did like owners manual said and used oil but I didn't use regular motor oil I used the same Valvoline diesel oil I got for it.

That's when I noticed that return line was the source of my leak and figure get that fixed since its easy enough.

That valvoline diesel, IS your regular motor oil, and what go in
the pump. What came out probably smelled like kerosene
because it was oil thinned with diesel... kero and diesel are
nearly identical.

Same type of fuel rated line will work in non pressure locations,
different size obviously.

Now correct me if I am wrong but it would not work from the lift pump to the filters would it cause doesn't the lift pump create pressure or am I just thinking of the lift pump like a mechanical fuel pump on a conventional engine.

You COULD run fuel rated rubber from tank TO the injector
pump, and from injector leak off to tank.

Hard lines ONLY from injector pump to individual injectors
obviously.

That is how it is now. After I get the building built I am seriously thinking of custom bending me replacement hardline from the fuel tank shut off valve to the lift pump and from the lift pump to the filter assembly and from the filter assembly to the injection pump.

I don't know why the previous owner desided to cut the lines and install rubber hose. The hard lines from the injection pump to each injector are fine and intact.

Nights lost them or damaged them.. who knows.

Does it have the Simms pump? If so, the parts site shows hard lines with short sections of rubber hose for the lines from the lift pump to the filter and again from the filter back to the injector pump.

Fuel system parts diagram for 3000 with Simms pump

I believe mine is a simms pump. But there is no small lengths of rubber hose on mine. From the fuel shut off valve to the lift pump is just one long rubber hose on mine courtesy of the previous owner.

If I can locate new hardlines that are not too expensive I will consider just buying replacements vs making. But I am already looking at just replacing my power steering ram cylinders as the last couple times I been down the shaft is starting to have rust pits in it now and not sure if its worth me wasting time on rebuilding the orignals.



Thing is though looking at that diagram just like in my shop manuals it shows the hardline attached to the bottom side of the lift pump goes to the fuel filters. Mine isn't like that though, the manual lever for priming the system is on the left side of the lift pump when facing the pump and the bottom fitting is actually attached to the fuel shut off valve at the tank and the top fitting on the lift pump actually goes to the fuel filters on mine. I don't think mine could have been altered as I have been running it since we got it and it never stopped running but that one time when it was runned out of diesel as the valve was off and had to reprime the system.

Mine are plastic on a '65 and Ford has a replacement that has the
hose and the collars that fit around the injectors as an assembly.
Wasn't much and did the trick.

Mark