Replacing The Feed Line ['96]; Dissected Fuel Line

[tomblue01]

What's Really Inside After All These Years

My truck is 22yrs old. While the steel lines look fine, once I replaced them I noticed a 3psi increase!

Here's the inside of my steel fuel line. [The violet line: dremel cutting wheel has been consumed; turns out that was my last one! The green line: finger & dry paper towel rubbed off the buildup - there doesn't appear to be any significant interior rust. [truck lives below the MD line.]]

 

[tomblue01]

Why I Replaced The Feed Line / Feed Line Data

I had low pressure fueling issues. Upon replacing a faulty LP, I noticed some slight rust/crud on the inside of my 90* 1/2" hose barb--1/2" npt fitting. That set me to ponder my entire feed line setup. Did it have similar crud inside?

From tank to the pre-heater, there's roughly 12' 11" of fueling hose [club cab]. There's 3 separate flexible segments & 3 pre-bent steel segments. Therefore, from the tank to the pre-heater, there are seven connections that can potentially introduce air into the fuel system.

The steel tubing is 3/8" OD[feed only; return line is smaller] while the flex segments are 3/8" ID. The steel tubing has an inner diameter of ~ 0.305". Three-eighths of an inch = 0.375".

Replacing the feed line would do three things for me:
1. Reduce the points of failure to two.
2. Increase the diameter of the feed line by 0.070" to a uniform 0.375".
3. Ensure my system didn't have any interior rust/crud.

Since I was already working on the pre-IP side of the house, I decided to replace the original DC fuel line setup. <-- Good call! Recommend it!

 

[tomblue01]

Materials Used

14' of marine grade fuel hose, 3/8" ID [it is better to have and not need...]
2 hose clamps
a 3/8" straight hose barb--3/8" npt adapter [installs at the top of the pre-heater]
a small tube of Harvey's TFE paste [applied to 3/8" npt threads. do not use that white teflon/plumber's tape, as diesel eats away at it]
zip ties

 

[tomblue01]

Procedure

Tilt truck bed.
15mm socket. Remove the four D-side bolts holding bed down. Loosen the four P-side bolts. They dropped down about an inch, yet remained securely threaded to the bed. Unplug D-side rear brake/signal lamp. Unscrew the fuel filler neck. Get help - an extra set of hands needed here. Lift bed as high as it can go. Use multiple 2x4's to prop the bed up. Now you have access to the top of the fuel tank! Feed line on the right--towards rear of the truck.

Remove old line.
10mm socket. Remove the bolts retaining the existing feed line. The ones running along the frame came out easily. The one behind the fuel filter put up a good fight!
cable cutter/tin snips/big dikes. Cut the rubber portion of the feed line behind the fuel filter for easier removal.
large flathead screwdriver. Used to help pry the steel lines from their retainer near the fuel tank. Combined with a pulling out motion, the fuel line will pop out and not disturb the other lines [brake & return fuel].

Remove the pre-heater/pre-filter assembly. Because the LP is colocated, it has to come off too. Now, some may argue that removing the assembly isn't needed in order to replace the npt fitting there. Technically, they're right. I removed the assembly in order to clean out the threads and ensure a proper installation of my new fitting. As always, the choice is yours!

((I got logged out. Lost a ton of stuff. Not in the mood to repost right now.)) =[

 

[tomblue01]

Since I just lost a bunch of work, I'll come back later touch up the post. Real life calls!

 

[tomblue01]

As many will recognize, I've eliminated the pre-heater as it had burnt out.
She fires up immediately. [It's winter, & she's not garaged [sadly]]. I went from 24psi to 27psi at idle after installing the new feed line!
Everything up to the IP is new: LP, fuel filter, WIF [yes, I plugged it back in!], that short 90* hose, and the feed line.

 

[The patriot]

Nice neat job!
My only concern would be the flexible line sucking itself shut (or partially shut) while under vacuum.

 

[Bob4x4]

I did mine with 1/2 hose,most fuel hose of any quality will not collapse.

 

[The patriot]

Oh, Ok.
I'd still prefer as much hardline as reasonable.
I've seen fuel lines internally do funny things in class 8's that costed the owners a lot of $$$ trying to figure out, I suppose were not immune.

 

[Bob4x4]

Oh, Ok.
I'd still prefer as much hardline as reasonable.
I've seen fuel lines internally do funny things in class 8's that costed the owners a lot of $$$ trying to figure out, I suppose were not immune.

I did a road call on a Detroit diesel with a low power concern,bad neighborhood selling crack on the corner.Dropped the primary fuel filter to find a piece of 3/4 “ oak molding in it.They have a bit more suction then our little 5.9s

 

[RMcKinney]

Why I Replaced The Feed Line / Feed Line Data

I had low pressure fueling issues. Upon replacing a faulty LP, I noticed some slight rust/crud on the inside of my 90* 1/2" hose barb--1/2" npt fitting. That set me to ponder my entire feed line setup. Did it have similar crud inside?

From tank to the pre-heater, there's roughly 12' 11" of fueling hose [club cab]. There's 3 separate flexible segments & 3 pre-bent steel segments. Therefore, from the tank to the pre-heater, there are seven connections that can potentially introduce air into the fuel system.

The steel tubing is 3/8" OD[feed only; return line is smaller] while the flex segments are 3/8" ID. The steel tubing has an inner diameter of ~ 0.305". Three-eighths of an inch = 0.375".

Replacing the feed line would do three things for me:
1. Reduce the points of failure to two.
2. Increase the diameter of the feed line by 0.070" to a uniform 0.375".
3. Ensure my system didn't have any interior rust/crud.

Since I was already working on the pre-IP side of the house, I decided to replace the original DC fuel line setup. <-- Good call! Recommend it!

Hi RMcKinney 1995 Stock 2500,
I got a NAPA diesel inline filter. I routed the fuel line from the Lift pump through NAPA filter then the Truck filter.
I did not have to worry about the Pre-heater screen so plumbed the fuel heater out all together.