M1008 Rubber Fuel Hoses Sizes Lengths and Clear Poly Replacement

[Carl1008]

I wanted new (leak-free) clear (debuggable) flexible fuel hoses (or tubes, or even lines if, like me, you didn't know lines are the hard steel ones) in my M1008 and here's what I ended up using:

NEW TUBING:
I ordered McMaster Carr's Abrasion-Resistant Polyurethane Tubing for Fuels (McMaster sent me Randolph Tubing's Prothane II)
I tried to get tubing with an OD which was twice the ID because that's pretty much what you'll find in the stock m1008 fuel system.
I ordered 1/4" 5/16" and 3/8" ID tubing.

If your steel lines are rusted, replace them with metal, not rubber hoses. Rubber fuel hoses, if they catch fire (like from an overheating transmission) acts like a fuse right back to the fuel tank. Ask me how my neighbor knows.

ORIGINAL RUBBER FUEL TUBING LENGTHS + SIZES:

Fuel Tank Sender ->
3/8" ID x 5 3/16" Long -> Hard Line ->
3/8" ID x 13.5" Long* -> Mechanical Fuel Lift Pump -> Hard line to front of truck->
3/8" ID x 10" Long -> Fuel Filter ->
1/4" ID x 17" Long -> Injection Pump -> Various hard lines -> 8 Injectors ->
Rubber return lines which I didn't replace, and therefore didn't measure -> Hard Line to back of cab ->
1/4" ID x 5 3/16"*** -> Fuel Tank Sender's Return

Fuel Tank 'Drain'** [Third hard line on the Fuel Tank Sender] ->
5/16" ID x 3 15/16"*** -> short hard line which just goes a few inches over the frame rail ->
Seems to be capped off on my truck but, that might not be stock/correct.


Things I didn't replace or measure:
Fuel Filler Neck Rubber
Fuel Filler Neck Rubber Air Breather
Rubber return tubes coming out of each of the 8 injectors.

Tricks for getting to the fuel sender:

1. Disconnect tail lights
2. Disconnect rubber diff breather from bed! I forgot and stretched it, but it seemed to be ok.
3. Open the fuel door and disconnect the fuel filler neck by removing the 3 hex screws, not the three torx srews.
4. Use a wobble extension (DON'T Drill a hole in the bottom of each frame rail; See below) so you can access the nut for 3rd pair of bed bolts (counting from the front of truck)
5. Unbolt your 8 bed bolts. (If they spin, weld a flat bar to the heads of each pair of carriage bolts - think beefy safety wire.)
6. Don't forget to disconnect CB Antennas or Backup Cameras and whatnot. Ask me how I know.
7. To tilt up the bed, use a floor jack and a vertical 4x4 on the transverse support near the fuel filler. The 4x4 will sort of wedge against the bed's skirt and lock into place.
   View attachment 639578
8. Pile a lot of stuff under the bed so it doesn't fall and remove your head, or worse.
9. Remove the sender to check for rust in the tank or on the hard lines in the tank.
10. Do what you need to do to replace the rubber lines.
11. Replace the sender gasket. I had success with Advance Auto Parts' $9.80 DormanFuel Pump Tank Seal Part No E3004425897DOR
12. Installation is reverse of removal.
13. Tighten 8 big Bed Bolts to 50ft-lbs
14. Prime the fuel system according to the TM or, if you want to splurge on your truck and not worry about the leak-prone stock fuel filtration system, use the manual primer pump on your ~$125 Racor 230R10 Fuel Filter Water Separator with Primer Pump. (you'll need a 1/4" and 3/8" barbed to NPT fitting to adapt to the new filter)

Happy Wrenching.

* This was originally a complicated preformed rubber hose. I ended up carefully bending the steel hard line about 50 degrees to aim more directly at the pump to give a kink-free route for the new flexible tubing I was installing.

**The fuel tank sender's 'drain' tube doesn't have a dip tube, so IDK how it would function as a drain. A diesel tech I talked to said it should be an air breather with a check valve to let air pressure out but to not let any water, mud, dust etc into the tank.

*** I might have mixed these two up, as now I have fuel dripping out of my drain and I don't see how that could happen if the drain does not have a dip tube going to the bottom of the tank. Anyhow, looks like time to take the bed off again. Good thing I still have my flat bar welded to my carriage bolt heads

 

[cucvrus]

Drill a hole in the bottom of each frame rail so you can access the nut for 3rd pair of bed bolts (counting from the front of truck

I work in the truck body business for 26 years. I wanted to advise against drilling any holes in frame flanges. That is the best way to crack and break a frame. The area that you drilled / cut out is the most vulnerable area of the frame for cracks and breakage. Did you ever drive any of the CUCV / trucks off road and see the flex between the bed and the cab? On some roads it appears the bed is loose on the frame because of the movement. NEVER drill frame flanges forward of the very rear spring mounts on a frame. The side of the frame is drillable for fasteners. I just wanted to mention that. Most of the frame strength is achieved by the smooth solid frame flanges. Sorry to be late on that information. Also the bed is easily removable with 4 ratchet straps and 4 - 5/16" eye hooks and a garage or barn to use as a lift point. I use the same eye hooks and straps to remove truck cabs and I have 6 anchored eye hooks for the M1009 bodies. It also makes a great time to pressure wash and paint / coat the frame while the cargo bed is off. Very easy to do cargo bed removal when you are alone. Good Luck.

 

[Carl1008]

Updated my post thanks to your expert advice.

How would you suggest I proceed?
- use my amateur mig-welding skills to fill in the holes (the holes I made are just big enough for a 3/8" extension)
- chamfer the holes nicely and keep an eye out for cracks in the future
- get an expert to weld them.
- add reinforcing?

Thanks for your attention,

-Carl

 

[Ackevor]

A bit late but if you don't think driving out my way is too far (HA!), I would weld it up for free. Again its probably too late but if you are using a 75/25 Co2/Argon mix or equivalent shielding gas for your MIG you can do pulsed stacks to fill the hole. 3/8" isn't all that large so simply make sure its nice and clean top and bottom (shiny metal) and no flammable coatings 2-3" around the weld zone. Pull trigger for 1-2 seconds, enough to create a deposit that provided 100% penetration, release and move over to stack another halfway next to the first, pull trigger and release, repeat until closed. Its like stacking puddles with 6010 Rod but you start and stop the arc on each puddle. It's how a lot of anodized aluminum is welded but works well for closing up steel holes if they are small enough, larger ones its always better to cut material to fill and weld around it.

How is everything since? Thanks for itemizing the sizes too, just what I needed.

 

[cucvrus]

Personally on this light duty truck I would not try to go back and repair what is already done. The cure may be worse then the illness. I would not weld on the flanges after you have been cutting and drilling on them. That will just weaken them further. I would just let it alone and I feel it will be fine. Eyeball it on occasion. Going forward keep that in mind when working on frames. Flanges are off limits between the axles. the frame face is fine you can drill a few holes in the face if needed. These older trucks are weak enough in the frame flange area. They do not have the strength of the newer frames at you find on modern light/medium duty trucks. But I feel you will be fine. Good Luck Keep your eye one the area and Happy Holidays.

 

[Carl1008]

Thanks guys! I'll take this as a reminder I should take a flashlight and give a good look next time I'm under the truck.

Ackevor, I'm glad the itemized list has been useful. If you'de like, let me know if I have the measurements [which I marked with a ***] correct. Then I can update my original post.

My truck's fuel system is doing well. I just need to get the guts to replace a few glowplugs. (I'm afraid they're swollen and might break off - so I'm afraid to start the repair). It starts pretty well on 5 cylinders anyhow and gets up to 8 in a few seconds.

Other recent events included a wheel bearing that failed on the highway in the middle of VT. Scary! A tow to a Walmart parking lot, a trip to the part store, a new inverter, dremel, sacrificed screwdriver to replace the lock pin in the wheel bearing lock nut, and 6 hours had me back on the road to my garage where I promptly replaced it all again properly. I've also have a leaky brake line which I'll be tracking down soon. That's a reminder not to put off replacing old (wet probably) brake fluid just because you don't have auto-bleeders. Find a friend, not excuses!

Oh! And I sanded and put a fresh coat of bedliner in the passenger footwells, cab corners, and rocker panels. Got to love camo trucks - new black spots fit right into the paint job - no masking needed.

Keep on trucking,
-Carl
1985 m1008 "The Dreadnaught"

 

[Tinstar]

I wouldn't delay replacing the glow plugs.
It will only get worse at the worse possible time.

Maybe with no Walmart parking lot or parts store close.

 

[dependable]

I've also have a leaky brake line which I'll be tracking down soon. That's a reminder not to put off replacing old (wet probably) brake fluid just because you don't have auto-bleeders.

Probably you know this, but your 1008 was originally filled with DOT 5 silicon brake fluid, which does not mix with DOT 3&4.