Fuel Tank Straps

[67GMC]

I blew the rear brake line just before the T-Junction to the wheels. I replaced the hose and then realized that the steel line was also leaking. Fixed that. When bleeding the brakes, noticed the brake line that does a 90 to the frame rail had a pin hole leak. Then looked up further and could see dampness. In other words needs new lines. Anyway, I decided to run new lines and everything seems to be clipped along the rail with the fuel tank in the way.
I dropped the tank but there are no straps inside the coffin. Is this normal? I see the straps for sale on RockAuto but the coffin was tack welded up to the frame so I guess it was a bit of a janky fix and would hold the tank up.
The brake lines look like 1/4" all the way to to the front. I want to do new hard lines for the fuel too. So, quick questions
-Do I need fuel tank straps or can the coffin hold the tank up (like it was)?
-Are the brake hard lines 1/4" up to the proportioning valve?
-The Jeep has the brake hard lines with the spring wound around. Am I good to just use 1/4" lines as a replacement (I've got Copper-Nickel lines to use
-I have about 15' of 3/8" steel fuel line. Is that the size I should use? Most of the fuel line is pretty rusty so not sure of exact dimension.
Sorry for all the questions. It's a 1984 Grand Wagoneer.

Thanks!

[Yeller]

3/8 is what I would use to run the fuel.

[sierrablue]

I don't remember for sure what the '88 had--I thought the straps went around both the coffin and the tank? There should be a couple straps somewhere in the system.

3/8 will work fine. All you really need for <250 hp is 5/16 (I looked it up when I was determining what size I needed for mine) but I think stock was most likely 3/8; at least that's what my '71 has in the stock sections.

Is your question on the brakes whether or not it needs the spring? I have no idea; I wouldn't think so, but I can't answer that question for you. I suspect the spring helps with longevity, but I don't know how critical it is.

[67GMC]

Thanks for the replies. Definitely no strap on the outside of the coffin on mine. I've been surfing youtube and saw some tanks with the strap inside. I was thinking of not putting the coffin back in but not sure if the straps will hold the tank. Still working on it today so will have more information later.
For the brakes, parts of the lines have the spring wound around it. I heard that might have been for off-roading but not sure. I don't have that so I'm just putting 1/4 line in.

[tgreese]

OEM fuel is 5/16" forward and 1/4" back. No Jeep came with 3/8" lines AFAIK. The big GM cars with big GM engines typically have 3/8" lines. No Fords do, also AFAIK.

The parts book shows straps for the plastic 1980 tanks. The 81J book from the Tom COllins site ('81-84) also shows straps. Figure 14-7900.

81Jgastankstraps.png

IIRC the lines that drop from the MC to the prop valve are 1/4". Is there stone guard on the these lines? I don't think so. Not really needed there.

The factory brake lines on the chassis are 3/16" size. You need to use this size so your fittings will fit into the cylinders, flexible lines and prop valve. If you use the proper size, you can reuse your fittings, which will more than make up for the cost of the right size tubing. Suggest you buy 3/16" nicopp and replacement stone guard. You can get the stone guard (aka gravel guard) in plated steel (like the original) or stainless. Available many places - I think I bought mine at Summit racing - recall Inline Tube sells it on eBay for a decent price. Can also get the nicopp line there for a good price.

[67GMC]

Thanks Tgreese. I'll have to look at how the straps connected. I assume they connected to the tank to the frame and then the coffin was the protection for it all. I just dropped the tank a few minutes ago. Right to the floor, nothing holding it up other than the coffin.
For fuel-That's disappointing. My 3/8" fuel line is, as you say, from GM trucks so it looked close to the rust belt lines I have now. I think I might still use it to save some money.

As for the brake lines, There's stone guard (thanks for the name) from the rear T to just after the wheels (on the way to the prop valve). It goes smooth in the frame channel, running next to the fuel hard lines. The steel fuel hard lines behind the coffin look great (surprising) so now I have to figure out if I pull out everything to fix the cancer at the front and rear or use unions with some short pieces. I'll have to do the math as the fittings are more money than the line. Plus I don't have the right size so would need adaptors.

I was just trying to fix a broken brake line and now into some real work. Oh well.

[67GMC]

OK-From the parts catalog, it looks like the straps just hold the tank to the coffin. I was thinking these were to hold the tank to the Jeep and then the coffin was just a shield. Since it hasn't had straps on it for many years (since there aren't any on it now on the ground). Do you think they're needed? Can't see what they would do as if the coffin shears off, it would take the tank and straps with it.

[sierrablue]

I would put them on just for the extra security, but that's just me. Frankly I'd put them on or rig up some other straps so I could eliminate the coffin altogether, as that's what caused the frame on the '88 to rot out--the coffin and its support bracket stored salt and junk that just sat on the frame and the coffin, causing the frame to rust out. That's just me, but I'm not a fan of that skid plate now that I know what it causes, and have experienced it firsthand.

[67GMC]

You're right about the rust on the frame. That coffin collected a lot of dirt and the frame rail was full of rust (including the rusted brake and fuel lines). The Ziebart undercoating was sprayed all over everything and I think that made it even worse.

The GMC trucks I've had had long coffin-like metal tanks and they sat in a plastic "shield" which I assume was to protect against rocks. IIRC the straps went around the plastic to hold up the tank/shield combination. I spray painted the tanks with rocker guard to be safe. Since this tank is plastic, it seems like overkill to have a 50lb metal box around it.

I'm waiting for the fuel lines anyway. It's nice not to have all the tank in the way for running the new brake lines and fuel lines. I'm going to go 5/16" instead of 3/8" since I didn't calculate that I need length for both feed and return on the fuel lines so don't have enough of my GM 3/8 stuff to work.

I will probably sand blast the coffin and spray it with rocker guard and re-install. Thanks.

[Kingdingaling]

I have an 88 and once you unbolt the skid plate /coffin!! It will drop and the tank will still be held by 2 straps!!

[67GMC]

I have an 88 and once you unbolt the skid plate /coffin!! It will drop and the tank will still be held by 2 straps!!

That's interesting. I wonder if that's stock. The pictures in the parts manual appear to show the straps holding the tank to the coffin for the 84. I've got the straps coming as I already ordered them and too late to cancel. I'll post back once they come in.

[67GMC]

OEM fuel is 5/16" forward and 1/4" back. No Jeep came with 3/8" lines AFAIK. The big GM cars with big GM engines typically have 3/8" lines. No Fords do, also AFAIK.

I just re-read this post and realized (as tgreese already said), the fuel feed and return are different sizes (!). This is also why the fuel sender has two different size hoses on it. Can't believe I didn't think about this. Need some more 5/16 tube now. My workbench looks like a fire sale at a parts store.

[67GMC]

Finally received the fuel tank straps. As expected, they just hold the tank to the coffin. Seems like overkill but I guess it would stop any vibration or friction of the tank rubbing. There's also a little rubber mat it sits on. I'm cutting up a door mat for that.
I posted a picture on Jeep forum if interested.

https://www.jeepforum.com/threads/fuel- ... s.4474857/

[devildog80]

Tank when dropped off my '84 GW and yes straps hold tank snug in the coffin, then coffin bolts to frame rail and up under body.

You probably already have this done, but here are pics when I dropped mine......in case you can use for reference.

20220423_180155 by Scott Weckerly, on Flickr

20220423_163928 by Scott Weckerly, on Flickr

20220416_125844 by Scott Weckerly, on Flickr

20220423_163906 by Scott Weckerly, on Flickr

20221022_103922 by Scott Weckerly, on Flickr

20221022_103908 by Scott Weckerly, on Flickr

20221022_103843 by Scott Weckerly, on Flickr

20221022_103823 by Scott Weckerly, on Flickr

20221022_103752 by Scott Weckerly, on Flickr

20221022_103719 by Scott Weckerly, on Flickr

[67GMC]

Thanks for the great pics. It looks a lot like mine does under there.

[sierrablue]

Holy that's solid! The '88 was NOT anywhere NEAR that clean!

[67GMC]

Has anyone run into a larger brake line fitting on the 1/4" line to the combination valve for the rear brakes? I have 1/4" line flare nut fittings. They are too small to go into the valve. The 5/16 (which wouldn't fit the line) are also too small. I have saved the flare nut that was on there but wondered if this is something odd? I can't figure out what size it would be to fit properly. I've flared it for now but wanted to use a new fitting into the combination valve.

[Yeller]

The flare nuts on combination valances and master cylinders are always large and have never put the brain power into figuring out why. They are typically the same size and thread count as fine thread bolts in 7/16, 1/2, 9/16, or 5/8” new nuts are available

Flare nut kit

https://www.amazon.com/Brake-Line-Fitti ... NrPXRydWU=

[67GMC]

Thanks for that. I ordered them. My parts drawers are filling up! I hate these one-off things it makes it hard for people to get work done when you only have a weekend to work on it. I found a pic of a GM prop valve that shows all the odd fitting sizes. I think it would be similar for our Jeep part.

https://www.jeepforum.com/cdn-cgi/image ... g.4186571/

[tgreese]

I was able to buy these larger nuts as part of a pre-flared pipe in nicopp at my local parts store. Not cheapest by the piece, but a way to get them individually.

More than similar, I expect.