Fuel Return Line Size

[tigercreek]

62 Ford 4000 4cyl diesel - newly acquired

Pulling all of the fuel lines for replacement (not injector lines). One line is different than the others.

All of the lines seem to be 5/16 EXCEPT the return line from the injectors. The size of the return at the injectors/engine block is a 5/16 nipple (brass - looks to be ground and modified) but the line where it enters the fuel tank is about 1/8. The return block at the tank will only accept a smaller line here - the return port at this block from the pump is 5/16.

Looks like they squeezed a 1/4 hose on a 5/16 fitting at the injectors and double clamped the hose to a 1/8 metal line at the tank.

While I am replacing things I want to put in the correct size injector return line. My shop manual doesn't mention anything about it.

Do I use a larger line and step it down at the tank or a smaller line and step it down at the injectors?

 

[sotxbill]

use large line from inj pump to injectors.. then a small line from last injector to tank. ideal is to allow the pump to self bleed and expurge all air quickly so the larger line at the inj pump helps this to happen quicker??????

 

[john in la]

Sounds like you have the double return line fitting.
One line is 1/8" from the stand pipe to the side of the block and goes to the tall pipe.
The other is same size as the injector lines (Think 5/16) and runs from the pump to the stand pipe. This one hooks to the shorter pipe.

 

[tigercreek]

Thanks.

Now I know to step everything down on that line to 1/8. You never know coming in behind the rigging that people do.

Since I'm just getting everything checked for running/soundness I'm probably just going to install brass nipples on all inlets with new fuel line before I go to fitting hard lines.

I think part of the problem with them running this thing was all of the ill fitting fuel connections and leaks. Hope to remedy all of that.

 

[Ecnerwal]

You do understand that you have to use hard line between the pump and the injectors, unless you have some very high pressure hose?

 

[tigercreek]

I'm only replacing the tank to filter/pump and return lines. The injector lines are good - the ONLY good lines.

 

[Norm Graves]

John, Where did you get that picture & where can I get one of those? I had to reengineer mine to keep fuel out of the oil because the stand pipe is missing. Sure would like to get one in there. All my friends think my little Ford is manufacturing fuel.

 

[john phillips]

you can get the return line from cnh for about $55 if memory serves me. i bought a copper line kit from napa for the oil pressure line that had sweat fittings and adapters that was mde of copper seemed to work pretty good and was less than $10(CHEAP) comapered to $87 for the steel line from cnh, you could probably use that for the return. dont waste time buying the filter to pump line from cnh it wont work, and napa has the same fittings you cant bend it enough to get it to work, used 2 barbed(?) fittings from lowes fuel line and hose clamps (ugly but works until i can come up with something else.

 

[CAROGATOR]

when you need to bend steel lines without a bender or tighter turns, pack the line with fine sand and bend away. that keeps it from collapsing when bending. then clean real well.

 

[john in la]

That is a picture of a stand pipe I bought. They are hard to find but some tractor junk yards may have them.

The stand pipe is not the way to fix your leaking fuel into oil. In fact if your pump seals are bad (most likely) the stand pipe will do nothing to cure that since the pump hooks to the short stand pipe.

 

[Norm Graves]

Stand pipe was the problem as it quit getting fuel in the oil after I routed the small return line into a catch can instead of the bottom of the tank. Thanks for the info I haven't tried any used parts places around here.